计算cos^4(π/8)+sin^4(π/8)=____ 怎么做的?

已知sin a=2cos a 计算⑴（sinα+2cosα)/(5cosα-sinα) ⑵tan(α+π/4) 计算：sin（3π /4 ) +cos (2π /3) - sin 150° + cos135°=? 计算sin^4(3π/8)-cos^4(3π/8) 计算cos^4(π/8)+sin^4(π/8)=____ 怎么做的? 计算sin²π/8-cos²π/8= sinπ/8cosπ/8根据什么公式计算? 计算cosπ/12*sinπ/12 已知tan（α+π/4）=3,计算2sinαcosα+6cos方α-3/5cos方α-6sinαcosα-5sin方α 计算sin^2 (π/4)-cos^2 (π/4) * cosπ+3/4π^2 (π/6)+sin3π/2 1.已知tanα=3.计算(4sinα-2cosα)/(5cosα+3sinα)的值2.sinαcosα=3/8,且 π/4 < α < π/2 ,求cosα-sinα的值.女女会十分感谢的! 计算：-1/2+cos^2（7/8π） 2sin^2（3/4π）-1 计算sin(α-π/4)+cos(α+π/4)的值. 化简sin(α-5π)/cos(3π-α)×cos(π/2-α)/sin(α-3π)×cos(8π-α)/sin(-α-4π) 怎样化简函数 cosπ/4cosπ/3-sinπ/4sinπ/3cosπ/4cosπ/3-sinπ/4sinπ/3 cos^6(π/8)-sin^6(π/8)=求值,[cos^2(π/8)-sin^2(π/8)][cos^4(π/8)+sin^4(π/8)+cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-cos^2(π/8)sin^2(π/8)]=cos(π/4)[1-[sin^2(π/4)]/4]==7√2/16 sin^4π/8 +cos^4π/8 (cos(π/8))^4-(sin(π/8))^4 sin^4π/8-cos^4π/8=?