sin^4(67.5度) -cos^4(67.5度)sin67.5度的4次方 减 cos67.5度的4次方..求值...................

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sin^4(67.5度) -cos^4(67.5度)sin67.5度的4次方 减 cos67.5度的4次方..求值...................
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sin^4(67.5度) -cos^4(67.5度)sin67.5度的4次方 减 cos67.5度的4次方..求值...................
sin^4(67.5度) -cos^4(67.5度)
sin67.5度的4次方 减 cos67.5度的4次方..求值
...................

sin^4(67.5度) -cos^4(67.5度)sin67.5度的4次方 减 cos67.5度的4次方..求值...................
先用平方差公式化为(sin^2(67.5度))+cos^2(67.5度))+(
sin^2(67.5度))-cos^2(67.5度))
显然,前面的(sin^2(67.5度))+cos^2(67.5度)=1 后面的=
(sin^2(67.5度))-cos^2(67.5度))用2倍角可化为-cos(2*67.5度)
也就是-cos135=cos45
答案是1+根号2/2

-0.66854266905956166981309320462652

sin^4+cos^4=1,求sin+cos= sin^4+sin^2cos^2+cos^2a= 4(cos(-90度)+i*sin(-90度))+3(cos(90度)+i*sin(90度))=? Sin(11/8pai) ,cos(5/4pai)比较大小和SIN(_2100度),COS(110度)比较. 计算：sin^67.5°-cos^67.5度 sinα-cosα×tanα-sin^4α-sin^2α×cos^2-cos^2α 求最后结果 已知sinα-2cosα=10求(sinα-4cosα)/(5sinα+2cosα) cos^4A-sin^4a 化简 化简 sin^4a-cos^4b 化简：cos^4θ-sin^4θ 化简cos^4b-sin^4b 化简cos^4x+sin^4x 化简:cos^4(X)-sin^4(X) Sin^4a-cos^4a= sin^4+cos^4的值域是 sin[arc cos(-1/3)-arc sin(-1/4)] 化简sin^4x-sin^2x+cos^2x 化简:sin^4 x-sin^2 x+cos^2 x