Correct option is B
Given:
2−1−cosαsin2α+sinα1−cosα−1+cosαsinα
Concept Used:
sin2θ+cos2θ=1 ⟹1−cos2θ=sin2θ ⟹(1−cosθ)(1+cosθ)=sin2θ
Solution:
2−1−cosαsin2α+sinα1−cosα−1+cosαsinα =2−1−cosα1−cos2α+sinα(1+cosα)(1−cosα)(1+cosα)−sin2α =2−1−cosα(1−cosα)(1+cosα)+sinα(1+cosα)(1−cos2α)−sin2α =2−(1+cosα)+sinα(1+cosα)sin2α−sin2α =2−(1+cosα)+sinα(1+cosα)0 =2−1−cosα =1−cosα