 For example, let it be required to prove the formula sin ( A - B) = sin A. cos В - cos A. sin В from the annexed figure, where ВАC' = A, and C'AD — В ; each angle being greater than a right angle.  The elements of plane trigonometry - Page 27by John Charles Snowball - 1837Full view - About this book
 | John Charles Snowball - Trigonometry - 1880 - 256 pages
...of the simple angles A and В was represented as less than a right angle, — as was also their sum. But of whatever magnitude these simple angles are,...example, let it be required to prove the formula Sin (A — £) = sin A cos B — coa A sin В from the annexed figure, where BAG'— A, and C'AD—B; each... | |
 | Thomas Kimber - 1880 - 176 pages
...subtend the same ungle when the observer is at a distance of b feet. Find the height of the staff. 14. Prove the formula sin. (A + B) = sin. A . cos. В + cos. A sin. B, taking the case in which A and В are each less than a right angle, and their sum greater than a... | |
 | Henry Nathan Wheeler - Trigonometry - 1882 - 244 pages
.... • . cos and cos i (A - В) = ±±£v±2^v sin l C. [20] sm | с ' Now substituting as before in the formula sin £ (A ± B) = sin ^ A cos | В ± cos ^ A sin i B (Plane Trig. [18]), we get sin с V sin a sin b s1n (.s — ' sin (.s — a) . /sin A sin (s —... | |
 | 220 pages
...cos B, 262 = c2 + a2 or a2, 62, c2 are in arithmetical progression. •Exercises 72. Prove that 1. sin (A + B) = sin A cos В + cos A sin В from the formula с = a cos В + 6 cos A. Д DA 4- В 2. tan— — = tan— — tan (45°- в), where tano... | |
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