若tan^2a+4tanα-5=0,求锐角α

tan²a+4tana-5=0
(tana+5)(tana-1)=0
可得：tana=-5 或 tana=1
因a为锐角,所以tana>0可得：tana=1
即：a=45°

tan^2a+4tanα-5=0,
(tanα+5)(tanα-1)=0
tanα=-5或tanα=1
∴锐角α=45°