sin^2a+sin^2β-sin^2a*sin^2β+cos^2a*cos^2β=1 证明恒等式?各位高手 教教我

【证明】Sin A+sin B=2Sin 22 sin(arccos(2sin(a)))= 若sin^2a sin^2(-a)化简 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b sin a+sin 2a +sin 3a +...+sin na怎么求和? sin a+sin 2a +sin 3a +...+sin na怎么求和? 化简sin^2a+sin^β-sin^2a*sin^2β+cos^2a*cos^β 已知sin(a)=2sin(b)求sin(a/2)/sin(b/2)的值. 证明sin^2a+sin^2β+1>sina*cosa+sina+sinβ 化简sin^(a-30°)+sin^(a+30°)-sin^a化简sin^2(a-30°)+sin^2(a+30°)-sin^2a 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a 化简:sin(-a)cos(2π+a)sin(-a-π) 化简Sin A + Sin 2A / 1+cos A + sin 2a+2sin方a/ 1+tan a =2sin a cos a 求证:sin 2a/1+sin a+cos a=sin a+cos a-1急 3 在三角形ABC中,已知（a2+b2）sin（A-B）=（a2-b2）sin(A+B) 求证：ABC是等腰或直角三角形(a^2+b^2)sin(A-B)=(a^2-b^2)sin(A+B),(sin^A+sin^B)sin(A-B)=(sin^A-sin^B)sin(A+B) sin^A*(sin(A+B)-sin(A-B))=sin^B*(sin(A-B)+sin(A+B)) sin^A*2c