If 2 sin α1+cos α+sin α=y, then 1−cos α+sin α1+sin α is equal to
1−cos α+sin α1+sin α=1−cos α+sinα1+sin α.1+cos α+sin α1+cos α+sin α=(1+sin α)2−cos2α(1+cos α)(1+cos α+sin‘α)=1+2sin α+sin2α−1+sin2α(1+sin α)(1+cos α+sin α)=2 sin α(1+sin α)(1+sin α)(1+cos α+sin α)=2 sin α1+cos α−sin α=y