Question 732417
Prove this identity:
2cos^2(x/2)=(sin^2x)/(1-cosx)
..
left side:
use cos half-angle formula:
2[√((1+cosx)/2)]^2=2((1+cosx)/2)=1+cosx
..
right side:(sin^2x)/(1-cosx)=(1-cos^2x)/(1-cosx)={{{(1+cosx)cross(1-cosx)/cross(1-cosx)}}}
verified:
left side=right side=1+cosx