题目应该是(a^2+b^2)sin(A-B)=(a^2-b^2)sin(A+B),三角形ABC的形状是等腰三角形或直角三角形,证明如下:(sin^A+sin^B)sin(A-B)=(sin^A-sin^B)sin(A+B) sin^A*(sin(A+B)-sin(A-B))=sin^B*(sin(A-B)+sin(A+B)) sin^A*2co...