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The correct evalution of `int_(0)^(pi//2) sin x sin 2x dx ` isA. `(4)/(3)`B. `(1)/(3)`C. `(3)/(4)`D. `(2)/(3)`

Answer» Correct Answer - D
Let ` l = int _(0)^(pi//2) sin x sin 2x dx = 2 int _(0)^(pi//2) sin^(2) x cos x dx `
Put ` t = sin x rArr dt = cos x dx `
` :. L = 2 int _(0)^(1) t^(2) dt = 2/3 [ t^(3) ] _(0)^(1) = 2/3 `


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