sin(π/2+α)=cosα,那如果sin(-π/2+α)=-cosα
问题描述:
sin(π/2+α)=cosα,那如果sin(-π/2+α)=-cosα
答
对的 sin(-π/2+a)=sin(π/2+a-π)=cos(a-π)=-cosa
sin(π/2+α)=cosα,那如果sin(-π/2+α)=-cosα
对的 sin(-π/2+a)=sin(π/2+a-π)=cos(a-π)=-cosa