Question

    If sin 2A = cos (3A - 60o) , then find the

    value of sec 2A.
    A √3/2 Correct Answer Incorrect Answer
    B 1/2 Correct Answer Incorrect Answer
    C 2 Correct Answer Incorrect Answer
    D 2/√3 Correct Answer Incorrect Answer

    Solution

    sin 2A = cos (3A - 60)

    When sin P = cos Q, then P + Q = 90o

    2A + 3A - 60o = 90o

    Or, 5A = 150o

    Or, 'A' = 30o

    Therefore, sec (2 X 30o) = sec 60o = 2

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