. Trigonometria. jacent,So is the cofine of the other term adjacent, To the fine of the term remote. That all thefe may more clearlyappear , The circular parts of therectangular triangle ABC , areplaced within the circle , and eve-ry of the fides are leile then qua-drants , and the two angles acute: And {fnpfofing a line to be drawn from A to H) the parts of the obliquang. triangle A C H, arc placed without the circle, and the two fides are leffe then quadrants., and thean- $ gles oppofitc to thefe fides are a- cute, the third angle oppofite to the quadrant is cbtufe. (XCjj^. Here note^that wh
. Trigonometria. jacent,So is the cofine of the other term adjacent, To the fine of the term remote. That all thefe may more clearlyappear , The circular parts of therectangular triangle ABC , areplaced within the circle , and eve-ry of the fides are leile then qua-drants , and the two angles acute: And {fnpfofing a line to be drawn from A to H) the parts of the obliquang. triangle A C H, arc placed without the circle, and the two fides are leffe then quadrants., and thean- $ gles oppofitc to thefe fides are a- cute, the third angle oppofite to the quadrant is cbtufe. (XCjj^. Here note^that when a comphment in the Propofittons doth chance to con- curre with a complement, in the circular parts , you mufl take the fine it felfei or the tangent itfelfe; be- caufe the cofine of the cofirse is the fine, and the cotangent of the cotangent is the tangent. As in the preceding triangle ABC, lee the terms givenbe AC, andCB, and let the angleA C B be inquired, I fay then,by the fecond Axiom of the fecond hereof,. <is4s the tangent of I G, equal to AC,Is to Radius I E ; So is the tangent of F H, equal to CB ?To the fine of FE the l,equalto A C B. ■Therefore* As the tangent of A C,\Is to Radius ABC j So is the tangent of Q B,To the cofine of A C B. A ,-. ^ t U^f^e S j4s f^e ^a<^0thecofl)}e,/ a C B. }P™ let the terms given be A B and B C, to find AG, I fay then, As the Radius H B, equal to Radius ABC,To the fine of B D, the complement of A B. ? \ So fine ofC H, the complement ofC B,yilofine of C G, the complement of A C. There- Trigonometria Entwine a. yt Therefore , As Radius, To enfine A B : So cofine C B, To cofine A C. And that the truth of thefe Propofitions may the better appear , I have fcrdown the Loga-rithmcsof thefe parts, to ihew their equality by the proportions of fines and tangents. Logarithm , Logarithm Tanr. A B, or angle A H B 47.
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