PLANE TRIGONOMETRY.-II. COMPLEMENTAL ANGLES-SUPPLEMENTAL ANGLES-TRIGONOMETRICAL CONCEPTION OF AN ANGLE-NEGATIVE ANGLES. IV. Complemental Angles. It was explained in Section II. that the complement of an angle (i.e., of an acute angle) is the difference between it and a right angle, or, in other words, its defect from a right angle; and it was stated that the function of an angle is the co-function of its complement-that is, sin. A cos. (90° — A). cos. A sin. (90° - A); and so on. Past Def. Je soutins. And so on for other functions. Fut. Je soutiendrai. COND. Pres. Je soutiendrais. IMP. Soutiens. SUB. Pres. Je soutienne. SOUVENIR (se), 2, to remember. (See TENIR.) Imp. Je soutinsse. IND. Pres. Je me souviens. Imp. Je me souvenais. KEY TO EXERCISES IN LESSONS IN FRENCH. 1. Did not most of your relations come to see you? 2. Many came. 3. What has become of the others? 4. I could not tell you what has become of them. 5. What will become of that young man if he does not apply himself to study ? 6. I do not know what will become of him. 7. I know that he will never become learned. 8. How many francs have you left? 9. I have only one franc left. 10. How much shall you have left, when you have made your purchases? 11. I shall only have a trifle left. 12. Has that apprentice become skilful in his trade? 13. He has become skilful in it. 14. Was that gentleman born blind, or has he become so? 15. He has become so. 16. Do you know what has become of those young people? 17. They have become doctors. 18. Do you not know what has become of my books? 19. They are mislaid. 20. Will you not become lame, if you walk so much? 21. I shall become lame and thin. 22. Did not the crowd lose its way in this wood? 23. The crowd lost its way in it, and could not find it again. 24. A crowd of barbarians desolated the country. 25. A crowd of ruined citizens filled the streets of Stockholm. EXERCISE 164 (Vol. III., page 165). 1. La plupart de vos amis ne sont-ils pas devenus riches? 2. La plupart sont devenus pauvres. 3. Cette demoiselle n'est-elle pas devenue savante? 4. Je pense qu'elle ne deviendra jamais savante. 5. L'armée américaine n'est-elle pas très-petite? 6. L'armée américaine est petite, mais la plupart des soldats américains sont très-braves. 7. Pouvez-vous me dire ce qu'est devenu ce monsieur ? 8. Je ne saurais vous dire ce qu'il est devenu. 9. M. votre frère est-il aveugle de naissance? 10. Non, Monsieur, il l'est devenu. 11. Êtes-vous né boiteux ? 12. Non, Monsieur, je le suis devenu il y a trois ans. 13. La plupart de vos heures ne sont-elles pas dévouées au jeu ? 14. Non, Monsieur, elles sont dévouées à l'étude. 15. Combien de votre argent vous reste-t-il ? 16. Il ne m'en reste que vingt-cinq francs. 17. Savez-vous combien il me reste? 18. Il ne vous reste qu'une bagatelle. 19. Combien vous restera-t-il demain ? 20. Il ne me restera que six francs. 21. Il ne me restera que deux francs, quand 22. Qu'est devenue votre grammaire? 24. Savez-vous ce qu'est devenu mon chapeau ? 25. Vous l'avez laissé sur la table. 26. Ce monsieur ne deviendra-t-il j'aurai fait mon emplette. 23. Je l'ai égarée. (27) The above may, however, be thus proved geometrically:π A. In Fig. 4, let CA BA; then BA F= Make GAF= 2 CAB (whence C AGBA F). Note that AB=AG= = radius. AGH and BAD are easily shown to be similar triangles, whence, Fig. 4. 2 V. Numerical Values of certain Trigonometrical Ratios.It was stated in the last lesson (Section II.) that the ratios of certain angles could be worked out geometrically. These angles are 45°, 60° (and therefore 30°, its complement), 18° (and therefore 72°). We select 45°, 60°, and 30° as specimens, and work to five places of decimals:By (7), sin. 45° + cos.2 45° = 1. But since complement of 45° = 45° (for 90° sin. 45° = cos. 45°, and sin.2 45° = cos.2 45°, ... 2 sin.2 45° 1, and 2 cos.2 45° = 1. 1 and sin. 45° = 2' √2 .. sin. 45° = Similarly, cos. 45 0.70710. sin. 45° cos. 45° And by (10), cotan. 45° = 1. By (11), tan. 45° = 45°), 76 The above results can be verified by constructing a right- | being examined, but by dropping the perpendicular DG on to angle B (.. of 45° angled triangle, as in Fig. 3, with angle A = CA produced. each), where side a side b, and consequently tan. A = tan. sin. DAG; Sin. CAD is therefore DG But DG A D is also ... sin. CAD = sin. D A G. = But since DAG CAB, and triangle A D G evidently tri angle A B C, D G BC = ; AB .. sin. C A D (an angle in second quadrant) sin. C A B (an angle in first quadrant). DAG, CAB is the supplement of CAD; Also A C = But since CAB √3 = = 0.86602, As we know the ratios of 60°, we of course know the ratios of 30°, its complement. VI. Supplemental Angles.-The supplement of an angle (less than two right angles) is the angle wanting to complete it to two right angles, or 180°. Thus the supplement of 30° = 180° 180° 175° 5°, and so - 30° 150°; supplement of 175° In sexagesimal measure, supplement of A = 180°- A. In circular measure, supplement of A = - - A. VII. Trigonometrical Conception of an Angle-Functions of Angles exceeding 90°-Use of the Signs + and The trigonometrical idea of an angle being a quantity to bo calculated rather than, as in Geometry, a shape to be drawn, we find ourselves quite untrammelled by compass and pencil, and may therefore deal not only with angles exceeding 180°-which a geometer could only describe as angles turned inside out-but with angles of any number of degrees whatever, even exceeding 360°. We shall, however, find that the functions of every angle exceeding 90° are the functions of some angle below 90°, so that practically we have no need to calculate ratios for angles out of the first quadrant. Indeed, it is obvious that Fig. 2 cannot possibly be constructed for any angle not less than a right angle. It is a conventional arrangement in this science that all positive angles (for definition of negative angles see Sect. IX.) are supposed to start from above a kind of horizontal base-line, which forms one side of the angle, the other being supposed free to revolve, in the direction of the arrows in Fig. 6, through an arc of any number of degrees, whether greater than an entire revolution or not. In Fig. 6 let A c be the "baseline" of the angle C A B (less than 90°, or "in the first quadrant"). Produce CA to G. Now let A B, the "free side," revolve to the position A D, making DAG = CA B, and AD = A B. Then CAD is more than 90° and less than 180°, or is "in the second quadNow there is clearly no way of constructing, for the angle CAD, the right-angled triangle which played so important a part in Fig. 2, in determining the ratios of the angle then rant." 270 or, sin. (180° — A) = sin. A.S (28) From this it appears that the same ratio applies to more than one angle. A remedy for the confusion which might thus arise is found in the following arbitrary use of the signs + and A perpendicular drawn upward from a given base is considered opposite in sign from a perpendicular drawn downward; and a line drawn to the right of a given point of opposite sign to a line drawn towards the left from the same point. Conventionally, lines measured to the right of a given point are regarded as +, therefore corresponding lines to the left are - ; and lines drawn upward are +, and downward By this arrangement it appears that, in Fig. 6, BC, DG, and A C are positive, while C F, G E, and AG are negative quantities. As no negative quantities enter into the ratios of any angle in the first quadrant, its functions are all + or positive. And the cosine of an angle in second quadrant is negative. and the sine and cosine of an angle in the third quadrant are both negative. If A E revolve further to A F in the fourth quadrant, making a (trigonometrical) angle C A F of more than 270°, but less than 360°, then, making CAF=CA B, and noting that E c is negative and AC positive, we find by precisely similar reasoning that sin. (360° A) = = sin. A; . (31) cos. (360° A) = cos. A. Thus the sine of an angle in the fourth quadrant is negative, and the cosine positive. = say that a function of any angle is the same function of the difference between it and the nearest even number of right angles. Thus, taking into account the signs which affect the different quadrants, sin. 200° : sin. (200180)° sin. 20°; sin. 275° sin. (360-275)° = sin. -85°; sin. 420° sin. (420 - 360) = sin. 60°, and so on. cos. A Since tan. A= sin. A' are in the first and third quadrants, where sin. and cos. have the same sign, and in the second and fourth, where sin. and sin. A and cot. A = cos. A' both tan. and cot. The other functions of angles 180° and 270°, except as below stated, are easily obtained as before, and appear in the following table, which sums up the results of the last two sections : RATIO. Sine Cosine Tangent Secant. Since 0 is the utter negation of all quantity, it is impossible to attach a sign to it. This accounts for the absence of the minus sign-evidently required by the symmetry of the above table-against sin. and tan. 180°, and cos. and cot. 270°. From this cause erroneous values (as regards sign) would be obtained for cosec. 180° and sec. 270° if we trusted in their case to formulæ (14) and (15), lately adverted to. To find cosec. 180°: - 1 sec. 180° cosec. 180° = /sec.2 180° -1 √1 By (23), (10), and (24), cosec. 270° cosec.2 270° - 1 By (20), - S. = To find sec. 270°. sec. 270°: = This proves indirectly that sin. and tan. 180°, and cos. and cot. 270°, have merely lost their minus sign through the accident of being represented, as to value, by 0. It will be observed in the above table that no ratio changes its sign except in passing through the values 0 or . The above curious diagram (Fig. 7) shows at a glance the fluctuations in the value of the several ratios in passing through the four quadrants, and will be more easily borne in mind by many than any written account. Its evident symmetry and completeness also indicate the justice of employing the signs + and in the arbitrary manner before explained. The propriety of so using those signs in dealing with lines can, however, be proved mathematically. Trigonometry, in its higher form, has been defined as "the consideration of alternating or periodic magnitude," and these words will be more easily grasped by the pupil with this diagram before him. IX. Negative Angles.-An angle starting from below the base When, at 180°, A B (or A D) again coincides with AG, D G dis- line A C in Fig. 6, by the movement of its free side in a direction appears, and If AB (represented now by A E) revolve further to 270°, EG quadrant of a negative angle the sine differs in sign from the coincides with A E, and A G disappears. LESSONS IN GREEK.-XLIV. THE VERBS IN μι. THE chief peculiarity of the conjugation in uu consists in this, that the verbs which belong to it, in the present, the imperfect, and several in the second aorist active and middle also, take special person-endings different from those of the conjugation in w, and in the indicative of the other tenses want the moodvowel. The formation of all the other tenses, with a few exceptions, coincides with the formation of the verbs in w. Several verbs in μ which have a monosyllabic stem, take in the present and imperfect a reduplication, which consists in this, that when the stem begins with a single consonant or a mute and a liquid, the first consonant of the stem is repeated with, or if the stem begins with σT, TT, or an aspirated vowel, an aspirated precedes the stem; as The verbs in μ are divided into two chief classes : The second person singular imperative present throws away the ending e, and in compensation the short characteristic vowel is lengthened—that is, a is changed into ŋ, e into e, inte ou, and u into ; thusἱ-στα-θι becomes ί-στη. δι-δο-θι The ending in the present is preserved in only very few verbs. In the second aorist of τιθημι, ίημι, and δίδωμι, the ending has been softened into σ: thus, e-T becomes des; δι-δου. τι-θε-τι becomes τι θει. δεικνύ-θι δεικνύ. 1. Such as append the person-endings immediately to the -és, do-01 = dos. In the second aorist of iarnμ, however, stem-vowels. The stem of this class ends in a, as i-σrn-μ, I place; stem ΣΤΑ. ΘΕ. stem ΔΕΙΚ. OM. In a liquid, as oμ-vi-μ, I swear; Of this second class only the verb oße-vvõ-μi (ΣBE), I extinguish, and imperative of the present and imperfect they retain rai and In the dual and plural of the optative imperfect the n is com. monly dropped, and the termination of the third person plural, is usually shortened into ev, as— τιθει-ημεν ησαν, = τιθειμεν. τιθείησαν = τιθείεν. ἱσται-ητε διδοι-ησαν ἱσταιτε. σο in their full forms; yet επιστω, ηπιστω; δύνω, ήδύνω; πρίω, Empi, are the regular forms of good prose. FORMATION OF THE TENSES. In the tense-formation of the entire active, as well as of the middle future and first aorist, the short characteristic vowel is lengthened-a into n, e into n and into e (in the perfect active of Tienu and inui), also o into w; but is retained in the other tenses of the middle and in all the tenses of the passive w, excepting the perfect and pluperfect of Tenui and inui, which receive the et of the perfect active (τέθεικα, τεθειμαι, είκα, είμαι). The first aorist active and middle of τίθημι, ίημι, and διδωμι have for their tense-characteristic not σ but κ :--ε-δω-κ-α. e-On-κ-α, ή-κ-α, The forms of the first aorist active, e0ŋka, nêu, and edwкa, however, are used only in the indicative, and especially in the singular; in the other persons commonly, and always in the other moods and the participle, the forms of the second aorist are employed. So instead of the forms of the first aorist middle οἱ τιθημι, ίημι, and διδωμι, those of the second aorist middle are used. On the contrary, the indicative forms of the singular second aorist of τιθημι, ίημι, and διδωμι (εθ-ην, ἣν, and εδων) aro not to be employed. The verb iornu forms the first aorist active and middle like the verbs in w, with the tense-characteristic σ, as €-OTN-O-G ε-στη-σ-αμην. The second aorist middle eσrauny is never used. Some other verbs, however, have the form, as many, man. The second aorist passive and the second future passive are wanting in these verbs; also the third future, except in iorqUI —έστηξω, οι έστηξομαι. In regard to the signification of iornu, observe that the present, imperfect, future, and first aorist active have the transitive import of to place. The second aorist, the perfect, and the pluperfect active, and the third future, on the contrary, have a reflex or intransitive meaning, to place oneself, or to stand. με 2. THE SECOND CLASS OF THE VERBS IN μ. The tense-formation of the second class of the verbs in has no difficulty. After cutting off the termination vvu and vui, In the optative second aorist of the verbs iσrnμi, Tienui, add the tense-forms to the stem. The verbs in o which lengthen this o into w in the present, retain the w in all the tenses, as στρωννύμι, ῥω-ννύμι, ἑω-ννύμι, χω-ννϋ-μι; future στρωσω, ¿w-ow, św-ow, xw-ow, and so on. But the verbs whose stem ends in a liquid take for the formation of some tenses a theme ending in a vowel, as oμ-vu-μi, aorist wu-o-oa, from the theme OMON. The second aorist and second future passive are found in only a few verbs, as Čevy-vuμι, aor. 2 pass. εζύγην, fut. 2 pass. ζυγησομαι. REMARKS ON THE MODELS. In the dual and plural of the indicative, and in the other moods and the participle, for the first aorist active, the second aorist active is used. Instead of the forms e-on-a-juny, e-dw-ka-uny, first aorist indicative middle, the Attic forms are used. The middle optative forms of the imperfect and second aorist of the verbs in e, namely, or, as Tilouny, bouny, are preferred to those in et, ας τίθειμην, θείμην. The perfect and pluperfect, έστηκα, ἑστηκειν (but not είστη KELY), form the dual and the plural immediately from the stem, as perfect, ἑ-στα-τον, ἑ-στά-μεν, ἑστᾶτε, ἑστᾶσι(ν); pluperfect, ἑστατον, ἑστάτην, ἑστᾶ-μεν, ἑστᾶτε, ἑστᾶσαν; instead of ἑστηκεναι, ἑστᾶναι is usually employed. The participle runs ¿σTws, wσa, ws, gen. ŵros, wons, as well as eστηkws, via, os, gen. OTOS, Vias. With éσTaTov compare тeтλаμеv (TAA), and тevaμev, τεθνατε, τεθνάσι(ν), inf. τεθνάναι, from τεθνηκα, θνησκω (ΕΝΑ). KEY TO EXERCISES IN LESSONS IN GREEK.-XLIII. 1. The soldiers will defend themselves against the enemy. 2. Do EXERCISE 130.-ENGLISH-GREEK. 1. Η λεια ενεμηθη. 2. Νεμω την λειαν. 3. Η πολις τιμωρήσει τους πολεμίους. 4. Ω παί, μη αχθεσθητι ύπερ ὧν ημάρτανες ελεγχομενος. 5. Αγαθος παιδες ουκ άχθονται ὑπὲρ ὧν ἡμαρτανον ελεγχόμενοι. 6. Στρατευσομαι επι τας Αθήνας. 7. Οζουσι μύρων. 8. Η ψυχή εις ουρανόν αναπτήσεται. 9. Αγαθοι επ' αγαθώ χαιρουσιν. 10. Τους στρατιώταις επιτηδείων δει. 11. Αγαθος των παιδων επι μελήσεται, αγαθοι δε παιδες των τοκέων επιμελήσονται, EXERCISE 131.-GREEK-ENGLISH. 1. Even a slow man who is well advised can in pursuit catch a swiftfooted man. 2. The Athenians chose Themistocles general in the Persian war. 3. Ulysses came to the great hall of Hades. 4. What ever lot you may have taken, bear it and chafe not at it. 5. Do not trust very quickly before you exactly see the end. 6. Do not consider whether I am somewhat young to speak, but whether I speak the words of prudent men. 7. Mourn with moderation for friends who are dead, for they are not really dead, but they have gone before on the same road by which all must go. EXERCISE 132.-ENGLISH-GREEK. the Arab caravans from Gerrha. Their vessels in the Red Sea coasted Arabia Felix and Ethiopia, exchanging the produce of both these countries at Elath and Ezion-geber, in return for the commodities brought overland through Edom. The rich countries just referred to were the ancient Ophir, with which the Jews also traded, and whence were obtained gold, silver, ivory, apes, and peacocks. Meanwhile the Mediterranean was being slowly explored. Eventually the persistence of the Phoenicians extorted from the rulers of Egypt limited rights to the navigation of the Nile, and they were assigned a part of Memphis for warehouses and offices. It is recorded that they were the first who rounded the Cape of Good Hope about 600 B.C., having started from the Red Sea at the instance of Pharaoh Necho, and in three years circumnavigated Africa. This event is involved in considerable obscurity, though there seems little reason to doubt its occur rence; but, whether true or not, the discovery was turned to no account for many centuries. That the Phoenicians first passed the Pillars of Hercules is undisputed. Before Saul, the first King of Israel, had begun to reign, they had already ventured out into the Atlantic ; and the tin mines of Britain, and the amber lands of the Baltic, were probably visited by them before the days of Solomon. Long before this they had begun to frequent, and even to settle upon the isles of the Levant and the Egean. Cyprus in particular (the ancient Chittim) could be seen from their shores, and to reach it was one of their earliest efforts. Keeping near the shore, and guided at night by the stars, they gradually extended the length of their voyages. In the course of time they improved their skill in navigation and ship-building. The acquisition of wealth, whether by just or unjust means, appears to have been the sole object of their traffic. It was the universal custom to sell as slaves prisoners taken in war. The Phoenicians were ever ready to purchase any number of captives, and they would, it is said, when the chance offered, kidnap Greek and Hebrew children. The Greeks, amongst whom the Phoenicians at the first had settlements, suffered from their piratical habits, but they afterwards became powerful rivals to Phoenician commerce. The Greek ports, and the isles of the Egean, were closed against the Phoenicians, and, in alliance with the Etruscans, the Greeks expelled them from Southern Italy (Magna Græcia). But the desire for Oriental luxuries lessened the jealousies of trade, and Greece could not consistently deny herself Phoenician wares. In Sicily, Sardinia, and the Balearic Isles, the Phoenicians planted colonies, and successfully competed with the Etruscans. Colonies were gradually formed along the Mediterranean coasts. In Asia Minor and the Euxine, as well as Africa and the islands, the native tribes were taught husbandry, and thus to produce commodities valuable to Phoenician commerce. Carthage and Adramyttium, Great and Little Leptis, with several hundred smaller stations, arose in Africa. Spain was literally a mine of wealth; for gold, lead, and iron abounded; and silver was so plentiful that the merchants are said to have ballasted their vessels with it, and to have made all their utensils, and even their anchors, of it. The profit was beyond compute. The natives gladly accepted Tyrian ornaments and glass trinkets for that upon which they set no value, and the Phoenicians disposed of this beautiful metal in the East, where it was held, comparatively, in higher estimation than gold. When the supply thus procured failed, the Phoenicians became AND POLITICAL HISTORY the taskmasters of the natives, whom they enslaved and comOF COMMERCE. 1. Οι Αθηναίοι πολλους στρατιωτας είλον. 2. Ἡ πολις Επαμεινονδαν είλετο στρατηγον. 3. Θεμιστοκλής ύπο των Αθηναίων στρατηγός ᾑρεθη. 4. Ελθε, ω φίλε. 5. Ω' αγαθοι φίλοι, έλθετε δευρο. 6. Εαν πεινης, τούτο ήδέως εδεί. 7. Ο παις όσον είχεν εδηδοκεν. INDUSTRIAL CHAPTER V.-FIRST COMMERCIAL PERIOD (continued)PHOENICIA-MARITIME OR COASTING TRADE. TRANSPORT by sea, in lessening the labour, time, and cost of procuring commodities from distant countries, gave a new life to commerce, and indefinitely widened its scope. It was chiefly as carriers that the Phoenicians distinguished themselves. They were the earliest recorded sailors. They were already a nation when the Israelites entered the Promised Land. Homer refers to their seafaring habits, and their daring as traders and pirates, as facts established at a date of about 1,000 years before the Christian era. As we have already seen, they navigated the Arabian and Indian Seas, and brought to the ports of the Persian Gulf the products of Ceylon and Malabar, of the Indus and the Ganges, thus linking the elephant traffic of Hindostan with the caravan commerce through Babylon and Palmyra, and with Spain pelled to work in the silver mines. Thus these poor aborigines |