3π/43π/4
3π/43π/4tan3π/4-1tana+1/tana=-10/33tan²a+10tana+3=0(3tana+1)(tana+3)=0-1tana=-1/3
tanα+cotα=-10/3tanα+(1/tanα)=-10/3tanα=-3 或tanα=-1/3因为3π/4所以tanα=-1/3