化简:cos^2(a+45度)-sin^2(a+45度)cos^2(a+45度)-sin^2(a+45度)=(cosacos45°-sinasin45°)²-(sinacos45+cosasin45)²=1/2(cosa-sina)²-1/2(sina+cosa)²=2sinacosa=sin2a最后两步怎么来的0.0

化简(sin a^2/cos a +cos a)*cot a 化简:sin(-a)*cos(-a-兀)*tan(2兀+a) sin(180度+a)*cos(-a)/tan(-a) 化简:sin(-a)cos(2π+a)sin(-a-π) 化简Sin A + Sin 2A / 1+cos A + 化简sin^2a-cos^2a 化简sin(a/2)cos(a/2) 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180)15为15度 化简cos(a+b)cos(a-b)+sin^2b 化简2cos^2a-1/[2tan(45度-a)*sin^2(45度+a)] 已知cosa-cosb=1/3,sin-sinb=1/2.求cos(a-b)的值 化简:cos^2(a+45度)-sin^2(a+45度) 化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b sin^2a+sin^2b-sin^2a * sin^2b+cos^2a * cos^2b 化简 化简sin^2a+sin^β-sin^2a*sin^2β+cos^2a*cos^β 4.9-1/化简：[cos(a+15度)]^2+[sin(a-15度)]^2+[sin(a+180度)]*[cos(a-180度)].做出来都是1+sin(2a) sin^2a+sin^2a.cos^2a+cos^2a化简 化简：sin^4a+cos^2a-sin^2a-cos^4a sin a+sin 2a /1+cos a+cos 2a 化简. 化简sin^2(a)sin(3a)+cos^2(a)cos(3a)