 | Webster Wells - Plane trigonometry - 1887 - 158 pages
...71. By Art. 20, we have sin (x + y) by (11) and (12) cos x cos у — s1n x sm у Dividing each term of the fraction by cos x cos y, sin x cos у cos x sin у cos a; cos у cos x cos у tan (a; + y) = - : - : — cos x cos у sm x sm у cos x cos у cos x cos у... | |
 | Edward Albert Bowser - Trigonometry - 1892 - 392 pages
...Art. 23, tan (x + y)= sin (x + У) _ sin a; cos у + cos a» sin у cos (x + y) cos x cos y — sin x sin y Dividing both terms of the fraction by cos x cos y, sin x cos y cos x sin у f , \_ cos x cos У cos x cos .У ^ cos a; cos y sin a; sin y cos a; cos y cos a; cos... | |
 | Webster Wells - Trigonometry - 1896 - 240 pages
...= ип * cos у + га. . »in» ь .„ M,d ,10) cos x cos у — sin x sin у Div1ding each term of the fraction by cos x cos y, sin x cos у . cos x sin у cos x cos у cos x cos у tan (x + y) = . ' cos x cos у _ s1n x s1n у nos x cos y cos x cos y tan x + tan y (13) 1... | |
 | Webster Wells - Trigonometry - 1907 - 140 pages
...(4), cos (x = sin ж eos y + cosa; sin y , (g) ^ ( eos ж cos í/ — sin x sin y Dividing each term of the fraction by cos x cos y, sin x cos у cos x sin у cos i» cos у cos a; cos y tan (x +• y) = cos a; cos у sm a; sin у cos x cos у cos a; cos y tan a;... | |
 | George Albert Wentworth - Navigation - 1903 - 422 pages
...logarithmic computation. tan x + tan у cotx + cot у sin x sin у _ co8 X COS у cos x cos у sin x sin у sin x cos у + cos x sin у cos x cos у ~~ sin x cos у + cos x sin у sin x sin у _ sin x sin у 84 TEACHERS' EDITION. 1 a,n— 'i 08-1 (EXERCISE... | |
 | Fletcher Durell - Plane trigonometry - 1910 - 348 pages
...: - r— . cos(x + y) cos x cosy — sin x sin у Divide both numerator and denominator of the last fraction by cos x cos y. sin x cos у cos x sin I/ ™ , / \ cos я cos У cos я cos V Then, tan (x + y)= - - - < - — *-• cos x cos ?/ sin x sin... | |
 | George Wentworth, David Eugene Smith - Plane trigonometry - 1914 - 348 pages
...therefore true for all angles. Similarly, by § 87, cos (x' + y) = cos (90° + x + y) = — aia(x + y) = — sin x cos у — cos x sin у = cos x' cos у — sin x' sin y, by substituting cos x' for — sin x and sin x' for cos x as above. That is, § 91... | |
 | Leonard Magruder Passano - Trigonometry - 1918 - 330 pages
...expression for the tangent of the sum or difference of two angles we proceed as follows : cos x ± y) sin x cos у ± cos x sin у cos x cos 2/ T1 sin x sin ?/ sin x cos у cos a? sin у cos a; cos у cos a? cos 2/ " cos x cos ?/ _ sin x sin... | |
 | Greg Attwood - Mathematics - 2004 - 188 pages
...LHS 8 a 9 a cos Л cos ß - sin Л sin ß cos (Л + ß) sin ß cos ß sin ß cos ß = RHS с LHS = sin x cos у + cos x sin у cos x cos у _ sin* cpfy cpslcsiny cos * çps'y cps^x cos у = tan x + tan y = RHS d LHS = cos л: cos у - sin... | |
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Div1ding each term of the fraction by cos x cos y, sin x cos у . cos x sin у cos x... 