化简cos^4b-sin^4b
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
sin(a+B)cos(y-B)-cos(B+a)sin(B-y) 化简
cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简
sin(a)*cos(a)=4,那么sin(a) cos(b)=?
已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值
a*sin(pi/4 - x) - b*cos(pi/4 - x) = a*sin(pi/4 + x) - b*cos(
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(
已知a,b都是锐角,sin a =4/5,cos(a+b),求sin b 的值,速求!
若cos(a+B)*cosa+sin(a+B)*sina=-4/5,则sin(π/2-B)
已知4sin asin b=根号2,4cos a cos b=根号6,则cos 2a+cos 2b的值是?
化简[sin(2A+B)]/sinA-2cos(A+B)