Question

数学帮忙啊....

已知tanα=-1/3 计算 (sinα+2cosα)/(5cosα-sinα)
帮帮忙 作业啊

Answer 1

tana=-1/3
sina/cosa=-1/3
cosa=-3sina
原式=(sina-6sina)/(-15sina-sina)=-5/(-16)=5/16

Answer 2

分子分母同时除以cosα，(sinα+2cosα)/(5cosα-sinα)=（tanα+2)/(5-tanα)=(-1/3+2)/(5+1/3)=5/16