Hi i didnt undestand how the sin75 and sin30came there?

Dear student

Here it is reversed, however, we need to see how sin 75 *sin 30 came

sin(A+B).sin(A–B)

(sinA.cosB+cosA.sinB).(sinA.cosB-cosA.sinB)

[sin^2(A).cos^2(B)-cos^2(A).sin^2(B)]

[sin^2(A){1-sin^2(B)}-{1-sin^2(A)}sin^2(B)]

[sin^2(A)-sin^2(A)sin^2(B)-sin^2(B)+sin^2(A)sin^2(B)]

sin^2(A)-sin^2(B).

Regards

Approved