Question

    If cos θ + sin θ = m, sec θ + cosec θ = n then n(m

    2 – 1) is equal to?
    A 2n Correct Answer Incorrect Answer
    B 2m Correct Answer Incorrect Answer
    C 4mn Correct Answer Incorrect Answer
    D Mn Correct Answer Incorrect Answer

    Solution

    Put θ = 45°, then m = 1/√2 + 1/√2
    ⇒m = √2 and n = 2√2=2m
    So, n(m 2 –1) = 2m(m 2 –1) = 2m(2 – 1) = 2m

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