sin5

  1. A

    complex no. sin^5 x cos^2 x =

    p302 q12 question : prove that 2^6 sin^5 x cos ^2 x = sin 7x -3sin5x+sin3x+5sinx my working: let z = cos x + i sin x then z + 1/z = cos x z - 1/z = i sin x 2^6 sin^5 x cos ^2 x = 2^6 (z - \frac 1 z )^5 (z+ \frac 1 z )^2 = 2^6 (z^2 - \frac 1 {z^2})^2 (z- \frac 1 z)^3 expand the terms and...