求证sin(360-a)=-sina
求证:(1)sin3a=3sina-4sin^3a
求证sin(2A+B)/sinA-2cos(A+B)=sinB/sinA
5sinA=3sin(A+2B),求证tan(A+B)=4tanB
求证sina-sinb=2cos(a+b)/2*sin(a-b)/2这个怎么证明?
已知A,B,C是三角形ABC的三内角,且满足(sinA+sinB)平方—sin平方C=3sinA*sinB,求证:A+B
证明(sina+sinθ)*(sina-sinθ)=sin(a+θ)*sin(a-θ)
已知cot(a+b)=0求证sin(a+2b)=sina
已知cos(a+b)=0,求证:sin(a+2b)=sina
已知COS(A+B)=0 求证SIN(A+2B)=SINA
若sina+cosa=1求证sin^6a+cos^6a=1
求证sina+sinb=2sin(a+b)/2*cos(a-b)/2
求证cos^3a(1+tana)+sin^3a(1+1/tana)=sina+cosa