in this problem i have to prove

the inverse of cot (2) + inverse of cot (3) = pi/4

so i rewrote the problem in terms of inverse tan and got

inverse of tan (1/2) + inverse of tan (1/3)

after i get to this step im not sure where to go...i used triangles trying to figure out the angle measures and came up with some weird numbers...one triangle showed sin = 1/sqrt of 5 and cos = 2/sqrt 5. the other triangle shows sin x = 1/sqrt of 10 and cos x = 3/sqrt of 10? any help would be appreciated. thanks in advance