sinπ8.cosπ8=

sinπ/8cosπ/8=()sinπ/8cosπ/8=1/2sinπ/4=1/2*√2/2=√2/4sinπ/8cosπ/8=(√2/4)原式=1/2sin(π/4)=四分之根号二0.5*Sin45'

cos5π/8cosπ/8+sin5π/8sinπ/8=cos5π/8cosπ/8+sin5π/8sinπ/8=cos(5π/8-π/8)=cos(4π/8)=cos(π/2)=0原式=cos(5π/8-5π/8)=cos0=1

求SINπ/64COSπ/64COSπ/32COSπ/16COSπ/8只有类似例题、

计算sin²π/8-cos²π/8=sin²π/8-cos²π/8=-cos(2*π/8)=-√2/2sin²π/8-cos²π/8=-cos(π/4)=-√2/2

sin^4π/8-cos^4π/8=?sin^4π/8-cos^4π/8==(sin^2π/8-cos^2π/8)(sin^2π/8+cos^2π/8)=sin^2π/8-cos^2π/8=-cosπ/4=-√2/2我用MATLAB给你算了

cos(3π/8)*sin(5π/8)=?原式=-cos(3π/8)*sin[π-(5π/8)]=-1/2*sin(3/4π)=-√2/4

sinπ/8×cosπ/8sin(π/8)×cos(π/8)＝(1/2)×sin(π/4)＝(1/2)×(√2)/2＝(√2)/4（倍角公式sin2α＝2sinαcosα）

sinπ/8×cosπ/8这个是二分之一的sinπ/4也就是√2/4,建议你多看看二倍角公式,你现在应该高二吧,马上你们就会学到,二倍角是和角公式的特殊形式,以后用多了就会熟悉了,不懂的话还可以问

sinπ/8*cosπ/8原式=1/2*(2sinπ/8cosπ/8)=1/2*sin(2*π/8)=1/2*sin(π/4)=1/2*√2/2=√2/4

cosπ/6=(),sinπ=()cosπ/6=根号3/2sinπ=0你用计算器不就得了。

sinπ/12*cosπ/12=?原式=(2sinπ/12*cosπ/12)/2=sinπ/6/2=(1/2)/2=1/4

sin(π/12)-cos(π/12)=0[sin(π/12)-cos(π/12)]²=sin²(π/12)-2sin(π/12)cos(π/12)+cos²(π/12)=1-sin(π/6)=1/2∵sin(

cos(a+π/2)=sin?负的sinα

cos^2(π/4+α)=(cos(π/4)cosα-sin(π/4)sinα)²cos^2(π/4+α)是怎么等于(cos(π/4)cosα-sin(π/4)sinα)²的?因为cos(π/4+α)=(cos(π/4)

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(

已知(sinα-cosα)/(sinα+cosα)=1/3,则cos^4(π/3+α)-cos^4(π/6-α)的值为答案好像是（3-4√3）/10[cos^4(π/3+α)]-[cos(π/6-α)]^2=[cos(π/3+α)]^4-[

已知α+β=π/3,则cosαcosβ-√3sinαcosβ-√3cosαsinβ-sinαsinβ的值为（）A.-√2/2B.-1C.1D.-√2cosαcosβ-√3sinαcosβ-√3cosαsinβ-sinαsinβ=cos(α+

sinθcosθ=1/8,θ∈(π/4,π/2),求cosθ-sinθ的值(cosθ-sinθ)^2=1-2sinθcosθ=1-2*1/8=3/4又因为θ∈(π/4,π/2),所以sinθ>cosθ所以cosθ-sinθ=-√3/2

为什么-[cos²(π/8)-sin²(π/8)]=-cos(π/4)cos的2倍角公式.cos2x=cos²x-sin²x

不用计算器求值sinπ\8cosπ\8=sin^2π\12-cos^2π\12=化简：（cosx+sinx)^2=表示,照片已拍好,网速问题传不上来,只能手工打一下喽~第一个,根据二倍角公式sin2a=2sinacosa得到sinπ/4=2