化简sin^2a+sin^β-sin^2a*sin^2β+cos^2a*cos^β

化简sin^2a+sin^β-sin^2a*sin^2β+cos^2a*cos^β 化简Sin A + Sin 2A / 1+cos A + 化简:sin(-a)cos(2π+a)sin(-a-π) 化简sin^2a-cos^2a 已知 sin a,sin 2x ,cos a 成等差数列,sin a ,sin x ,cos a 成等比数列,求cos 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 化简：sin^2a+sin^2β-sin^2asin^2β+cos^2acos^2β sin^2a+sin^2a.cos^2a+cos^2a化简 化简cos^2(a+15)+sin^2(a-15))+sin(a+180)cos(a-180) 化简[cos(a-π)/sin(π-a)]sin(a-π/2)cos(π/2+a)= 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180) 化简sin(π+a)cos(-a)+sin(2π-a)cos(π-a)