sin(A+B)sin(A-B)为何可以化简为 -{cos^2(A)-cos^2(B)}?
为什么sin(a+b)-sina=2sin(b/2)cos(a+b/2)
sin(a-b)sin(b-r)-cos(a-b)cos(r-b)
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
sin^2 (A)+sin^2(B)-sin^2(A)sin^2(B)+cos^2(A)cos^2(B)
貌似不难,sin(a+b)cos(c-b)-cos(b+a)sin(b-c)sin(a-b)sin(b-c)-cos(a
sin(A+B/2)=cos(C/2)
证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2
sin(a+b)cos(a-b)怎么化简
化简[sin(2A+B)]/sinA-2cos(A+B)
cos(a-b)cosb-sin(a-b)sinb
设向量a=(cos(a+b),sin(a+b)),b=(cos(a-b),sin(a-b)),(括号里的为阿尔法,贝塔)
已知向量a=(sin(A+B)/2,cos(A-B)/2-3根号2/4) 向量b=(5/4sin(A+B)/2,cos(