Prove that:
1. f(x) = tan2x.tan3x.tan5x then prove that
f ' (x) = 5sec25x - 3sec23x - 2sec22x
2. 1-cos A / sin A = tan A/2
Please reply with solution. Thank You.
1. Treat prod. of two as a group like (tan 2x tan 3x) tan 5x.Now apply diff. prod. rule treating bracket as one and tan 5x as other.
2. 1-cos A = 2sin2(A/2) & sin A = 2sin(A/2)cos(A/2).