如何证明sin(A-B)*sin(A+B)=sinA²-sinB²

如何证明sin(a+b)sin(a-b)=sin*a-sin*b (*为平方) 如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b) 怎样证明/sin a +sin b/ 如何证明在任何三角形ABC中 周长等于 a/sin A (sin A +sin B +sin C) 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 【证明】Sin A+sin B=2Sin 22 如何证明sinA2-sinB2=sin(A-B)*sin(A+B) 如何证明sin(A-B)*sin(A+B)=sinA²-sinB² sin(A+B)=sinAcosB+cosAsinB//如何证明? 证明sina sin(a+2b) - sinb sin(b+2a) =sin(a+b)sin(a-b) 懂得进.证明,sina+sin(a+b)+sin(a+2b)+...sin(a+nb)=sin(a+ab/2)sin[(n+1)b/2]/sin(b/2) sin(a+b)怎么证明的? 证明sin(a+b)=sinacosb+cosasinb SIN(A-B)怎么证明的? 证明sin(A+B)=sinAcosB+cosAsinB sin a-sin b等于 证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1 用正弦定理证明a+b/c=sin A+sin B/sin c