Question

6/tana=9/tan(45°-a）求a

Answer 1

先约分得2/tana=3/tan(45°-a),其中tan(45°-a)=（1-tana）/(1+tana),代入并整理得3(tana)^2+5tana-2=0,解得,tana=1/3,或tana=-1/2.所以a=arctan(1/3)或a=-arctan(1/2)