和差化积公式的推导（和差化积公式证明）

1、第一个公式的证明: 右边=2*sin[(A+B)/2]*cos[(A-B)/2] =2*[sin(A/2)*cos(B/2)+cos(A/2)sin(B/2)]*[cos(A/2)cos(B/2)+sin(A/2)sin(B/2)] =2*sin(A/2)*cos(A/2)*cos(B/2)*cos(B/2)+2*cos(A/2)*cos(A/2)*sin(B/2)*cos(B/2)+2*si...

2025-09-07