Question

cot u - cot 2u = cosec 2u

Answer 1

LS = cosu/sinu - cos 2u/sin 2u
= cosu/sinu - (cos^2 u - sin^2 u)/2sinucosu
= (2cosucosu - cos^2 u + sin^2 u)/2sinucosu
= (cos^2 u + sin^2 u)/2sinucosu
= 1/sin 2u
= csc 2u
= RS