Question

    sin10˚ x sin20˚ x sin40˚ =? 

    A 1/7 Correct Answer Incorrect Answer
    B 1/8 Correct Answer Incorrect Answer
    C 1/14 Correct Answer Incorrect Answer
    D 1/16 Correct Answer Incorrect Answer

    Solution

    We know that sin x x sin 2x x sin 4x = 1/4 sin 3x   So sin10  x sin20˚ x sin40˚ = 1/4 x sin(3 x 10˚) = 1/4 x sin 30˚   = 1/4 x 1/2  = 1/ 8  

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