已知tan(a派/4)=1/2.且-派/2

已知tan(a派/4)=1/2.且-派/2

tan(α+π/4)=(tanα+tan(π/4))/(1-tanα*tan(π/4))=(tanα+1)/(1-tanα)=1/2
=> tanα=-1/3
-π/2