tanα+1/tanα=-10/3
(tana)^2+(10/3)tana+1=0
3(tana)^2+10tana+3=0
(tana+3)(3tana+1)=0
tana=-3或tana=-1/3
∵3π/4<α<π
∴tana>-1
∴tana=-1/3
tanα+1/tanα=-10/3
(tana)^2+(10/3)tana+1=0
3(tana)^2+10tana+3=0
(tana+3)(3tana+1)=0
tana=-3或tana=-1/3
∵3π/4<α<π
∴tana>-1
∴tana=-1/3