(1-cosx)／(x^2)从负无穷到正无穷的积分怎么求？

已知α是锐角,且tan[(π除4)+α]=2,求(sin2α乘cosα－sinα)除(sin2α乘cos2α)tan(α+π/4)=(tanα+1)/(1-tanα)=2(tanα+1)=2(1-tanα)tanα=1/3α为锐角,sinα=1/√10cosα=3/√10sin2α=2sinαcosα=3/5matlab给出一个信号t=0:0.001:3,其正弦信号频率响应特性u=sin(300t...