Question

Prove that
(cosA-cosB)²+(sinA-sinB)²=4sin²(A-B/2)​

Answer 1

Answer:

Step-by-step explanation:

1+1-2(CosA.CosB+SinA.SinB)=2-2(Cos(A-B))

=2[1-Cos(A-B)]

=2[1- [1-2Sin²(A-B)/2] ]

=2[ 1-1+2Sin²(A-B)/2]=4Sin²(A-B)/2 =R.H.S