cos(a+b)cos(a-b)+sin(a+b)sin(a-b)=-3/5,求sin(3π/2+2b)
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
cos(a+B)×cos(a-B)=1/3,求cos^2(a)-sin^2(B)的值
Cos(a+b)*cos(a-b)=1/5 求cos ^2-sin^2
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
高一数学已知sin(π/2-b)*cos(a+b)-sin(π+b)*sin(a+b)=3/5其中a∈(3π/2,2π)
cos(a-b)=12/13,sin(a+b)=-3/5,求cos(pai/2-2a)
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(
sin^2 (A)+sin^2(B)-sin^2(A)sin^2(B)+cos^2(A)cos^2(B)
已知sin(a+b)=-3/5,cos(a-b)=12/13,且π/2
已知cos(a+b)=0,求值:sin(π+2a+b)-cos(-π/2+2a+3b)
cos(a+b)=cos(a)*cos(b)-sin(a)*sin(b) 用三角形证明
sin(a-b)=1,sin a=1/3,求cos b的值