Question

If sin(A + B) = sin A cos B+cos Asin B, then find the value of
sin75 .

Answer 1

Sol: Given Sin(A+B) = Sin A Cos B + Cos A Sin B. Sin 75 = Sin ( 45 + 30) = Sin 45 Cos 30 + Cos 45 Sin 30. Sin 75 = (1 / √2) ( √3 / 2) + (1 / √2) ( 1 / 2) = [ √3 + 1] / 2√2.