化简cos(a+b)cos(a-b)+sin^2b
sin(a-b)sin(b-r)-cos(a-b)cos(r-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
cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简
为什么sin(a+b)-sina=2sin(b/2)cos(a+b/2)
化简[sin(2A+B)]/sinA-2cos(A+B)
cos(a-b)cosb-sin(a-b)sinb
sin(a+B)cos(y-B)-cos(B+a)sin(B-y) 化简
sin(A+B/2)=cos(C/2)
化简 sin^4a-cos^4b
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
由cos(a+b)=cos a cos b-sin a sin b cos(a-b)=cos a cos b+sin a
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(