I need someone to solve this for me. I don't understand it so i'm hoping once i see how it solved i will be able to do the rest. Thanks a mill.

1) Using the identities for sin(A+B) and cos^2(theta)+sin^2(theta)=1.

Find sine 65 degrees, given that sin 40(degrees)=0.643 and sin 25(degrees)=0.423?