1:sin(a-b)=sin(-b+a)
1:sin(a-b)=sin(-b+a)
证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b,
【证明】Sin A+sin B=2Sin 22
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
求证.(2),sin平方a+sin平方b-sin平方a*sin平方b+cos平方a*cos平方b=1
证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 并利用该式计算sin^2 20度=sin 80度
sin(a-b)=1,sin a=1/3,求cos b的值
已知锐角三角形ABC中,sin(A+B)=3/5,sin(A-B)=1/5
sin²A+sin²B=cos²C
1/sin(x+a)sin(x+b)的不定积分
cos(a-b)cos(b-c)+sin(a-b)sin(b-c)=
已知3SIN^2A+2SIN^2B=5SINA,求SIN^2A+SIN^2B范围