sec^2(x/2)等于多少?急
问题描述：
sec^2(x/2)等于多少?急
求证：1/tan(x/2) X sec^2(x/2) X 1/2 — cosx X 1/tanx X sec^2(x)=0 请务必详解.我找了好久没有找到反三角函数的变换...
答
sinx/(1-cosx) X 1/cos^2(x/2) X 1/2 -cosx X1/tanx X 1/cos^2(x)=0sinx/(1-cosx) X2/(cosx+1) X 1/2 - cosx X cosx/sinx X 1/cos^2(x)=0sinx/(1-cos^2(x))-cos^2(x)/sinx X 1/cos^2(x)=0sinx/sin^2(x)-1/sinx=0