求大神解:已知cosa=2m/(m^2+1).(m≤-1), .求sina,tana

问题描述:

求大神解:已知cosa=2m/(m^2+1).(m≤-1), .求sina,tana
求解答

cosa=2m/(m^2+1),sina=±√[1-(cosa^2)]=±(m^2-1)/(m^2+1),tana=sina/cosa=±(m^2-1)/(2m)