Question

sina/1+cosa+sina/1-cosa
упростить выражение

Answer 1

$dfrac{sin alpha}{1+cosalpha}+dfrac{sinalpha}{1-cosalpha}=sinalphaleft(dfrac{1-cos alpha}{1-cos^2 alpha}-dfrac{1+cosalpha}{1-cos^2alpha}right)=\ \ =sinalphatimes dfrac{1-cosalpha-1-cosalpha}{sin^2alpha}=dfrac{-2cosalpha}{sinalpha}=-2{rm ctg}alpha$