trigonometry!!!!!!!!!!!!!!!!!!!!!!

Question

how do I prove the following

2sin² (A/2) + cos A = 1

Answer 1

The given that  2sin²(A/2) +cosA = 1

2sin²(A/2) +cosA  = 2 [ 1 - cosA ]/2 +cosA      [ sin²(A/2) = (1 - cosA)/2 ]

=  1-cosA +cosA  = 1

Hence it is proved.