8sin(45+a)sin(45-a)=1,sin^4a-cos^4a=

8sin(45+a)sin(45-a)=1,sin^4a-cos^4a= sin(45度+a)= 已知sin a+cos a=m求cos a-sin a(45 cosA+cos^2A=1,sin^2A+sin^4A+sin^8A sin(a-15)=-sin(15-a)? sin(45+a)cos(45+a)怎么得=1/2sin(90+2a)? sin²A= 已知sin（45°+a）sin（45°-a）=-1/4,0° sin(arccos(2sin(a)))= sin(a)=5/13.a+b=45度,求sin(b).如题. 如果sin(125度-a)=12/13,那么sin(a+45度)=? 已知sin(45度-a)=5/13,求sin(25pai/4 + a) 当a=45度,sin a_______cos a当a＜45度,sin a_______cos a当a＞45度,sin a_______cos a 【证明】Sin A+sin B=2Sin 22 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 如何证明sin(a+b)sin(a-b)=sin*a-sin*b (*为平方) 求证恒等式sin(A+B)sin(A-B)=sin²A-sin²B 求证:sin(a+b)sin(a-b)=sin^2a-sin^2b