Question
Simplify the following trigonometric expression:
/>12 cos 68o cosec 22o - 3 cot 72o cot 18oSolution
12cos 68o cosec 22o - 3cot 72o cot 18o
= 12cos 68o cosec (90o - 68o) - 3cot 72o cot (90o - 72o)
Using, cosec (90o - A) = sec A and cot (90o - A) = tan A
= 12 cos 68o sec 68o - 3 cot 72o tan 72o
Since, sec A is reciprocal of cos A and cot A is reciprocal of tan A.
= 12 - 3 = 9
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