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    Question

    If 5sin²x + 3cos²x − 4 = 0, then find the value of

    sinx, given that 0° < x < 90°.
    A 1 Correct Answer Incorrect Answer
    B 1/√2 Correct Answer Incorrect Answer
    C 1/2 Correct Answer Incorrect Answer
    D √3/2 Correct Answer Incorrect Answer

    Solution

    Given
    5sin²x + 3cos²x = 4 Or,
    5sin²x + 3(1 − sin²x) = 4 Or,
    5sin²x + 3 − 3sin²x = 4 Or,
    2sin²x = 1 Or,
    sin²x = (1/2) Or,
    sinx = (1/√2) (since, 0° < x < 90°)

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