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If A is an acute angle and cot A + cosec A = 3, then the value of cos A is equal to:1. 4/52. 3/53. 1/54. 2/5 |
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Answer» Correct Answer - Option 1 : 4/5 Given: cot A + cosec A = 3 Formula used : cosec2 A - cot2 A = 1 cosec A - cot A = 1/ ( cosec A + cot A) cot A + cosec A = 3 ......(eq1) cosec A - cot A =1/3 .......(eq2) By solving eq 1 and eq 2 By elimination 2 cosec A = 3 + 1/3 cosec A = 5/3 = H / P \({H^2} = {P^2} + {B^2}\) \({5^2} = {3^2} + {B^2}\) B2 = 25 - 9 B2 = 16 base = 4 cosA = 4/5 |
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