Prove that sin 3 5 cos 12 13 sin 56 65 July 8, 2019 16 32 64 128 Prove that sin 1 3 5 )+ cos 1 12 13 )= sin 1 56 65 Cosa=1 3 cos(a+b)=-1 3 求a b∈(0 p 2)求cos(a-b)
