cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于4/5的过程.

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cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于4/5的过程.
cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于4/5的过程.

cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于4/5的过程.
cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2[cos(5π/12+π/12)+cos(5π/12-π/12)]
=cos^2(π/4+π/6)+cos^2(π/4-π/6)+1/2[cos(π/2)+cosπ/3]
=2cos^2(π/4)cos^2(π/6)+2sin^2(π/4)sin^2(π/6)+1/4
=2*1/2*3/4+2*1/2*1/4+1/4
=5/4

cos方5π/12+cos方π/12+cosπ/12*cos5π/12
=cos方(π/2-π/12)+cos方π/12+cosπ/12*cos(π/2-π/12)
=sin方π/12+cos方π/12+cosπ/12*sinπ/12
=1+cosπ/12*sinπ/12
=1+1/2*sinπ/6
=1+1/2*1/2
=1+1/4
=5/4

cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于5/4的过程. cos方5π/12+cos方π/12+cosπ/12*cos5π/12 最后等于4/5的过程. cos方π/8-1/2 化简cos方(π/4-α)+cos方(π/4+α) 化简cos方(π/4-α)+cos方(π/4+α) cos方-sin方=? 已知tan（α+π/4）=3,计算2sinαcosα+6cos方α-3/5cos方α-6sinαcosα-5sin方α 化简cos方(π/4-α)-sin方(π/4-α) cos方八分之π加sin方八分之π cos方(α-π/4)-sin方(π/4-α)得到在(0,2π)使sin方x>cos方x成立x的取值 sin方减cos方等于什么设sinα+sinβ=1/3,则sinα-cos方β的最大值是A 4/3 B 4/9 C -11/12 D -2/3cos方β=cos的平方β 已知sinαcosα=2/5,根号下cos2α=-cosα,则sinα+cosα=?根号两边平方不就是c方-s方=c方,那sinα=0 cos方α+cos方(α+β)-2cosαcosβcos(α+β)-sin方β 若sin方+cos方=1 那sin方-cos方等于什么 -1? 为什么a方=b方*sinA方+c方+b方*cosA方-2bc*conA.可以化简成 a方=b方+c方-2bc*cosA为什么a方=b方*sinA方+c方+b方*cosA方-2bc*conA.可以化简成 a方=b方+c方-2bc*cosA 是cos 题目中把一个cos打错成了con 已知：tan（π/4+α）=1/2 (1)求tanα的值； (2)求2sinαcosα-cos方α/2cos方α+sin方α