cosa=0.3 sin^4A-COS^4a=?

cosa=0.3 sin^4A-COS^4a=? cosA+cos^2A=1,sin^2A+sin^4A+sin^8A cosa-cosβ=4/5 sina-sinβ=3/5 求cos(a-β) Sin^4a+Sina*Cosa+Cos^2a化简 cos(a+30)cosa+sin(a+30)sina=? 已知a为锐角,3cos平方a-sin平方a-8cosa-4=0,则cosa=( ) 已知sina+cosa=m 求sina*cosa 和 sin^4a+cos^4a的值 若sina+cosa/sina-cosa=2,则4sin^2a-3sinacosa-5cos^2a= sin(a+kpai)=-2cos(a+kpai),k属于Z求(4sina-2cosa)/(5cosa+3sina) sin(a+kπ)=2cos[a+(k+1)π].求5cosa+3sina/4sina-2cosa sin(a+kπ)=2cos[a+(k+1)π].求5cosa+3sina/4sina-2cosa cosa=1/2,cos^4a+sin^4a=?cos2a=1/2 sin^4a+cos^4a=1,则sina-cosa= 若sin^4a+cos^4a=1,则sina+cosa= 已知sina-cosa=根号2/2,则sin^4a+cos^4a= 已知cosa=4/5,求sin^4a+cos^4a 已知cosa=1/4,则sin^4a+cos^4a 化简sin(π/4+A)cosA-cos(π/4+A)sinA=