Question

    If sin3A = cos(5A-30°), then what is the value of A? Given that 3A is an acute angle.

    A 16 Correct Answer Incorrect Answer
    B 15 Correct Answer Incorrect Answer
    C 29 Correct Answer Incorrect Answer
    D 10 Correct Answer Incorrect Answer

    Solution

    Always remember that sin & cos are compliment to each other So sin ɵ = cos( 90-ɵ) So it is given that sin3A = cos(5A-30°) Hence 3A + 5A - 30° = 90° So 8A - 30° = 90° or 8A =90°+30° = 120° or A =  = 15°

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