New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Simplify the following trigonometric expression: 12

    cos 68° cosec 22° - 3 cot 72° cot 18°
    A 1 Correct Answer Incorrect Answer
    B 15 Correct Answer Incorrect Answer
    D 9 Correct Answer Incorrect Answer

    Solution

    12cos 68° cosec 22° - 3cot 72° cot 18°

    = 12cos 68° cosec (90° - 68°) - 3cot 72° cot (90° - 72°)

    Using, cosec (90° - A) = sec A and cot (90° - A) = tan A

    = 12 cos 68° sec 68° - 3 cot 72° tan 72°

    Since, sec A is reciprocal of cos A and cot A is reciprocal of tan A.

    = 12 - 3 = 9

    Practice Next

    Relevant for Exams: