Inverse Trig Equation (1 Viewer)

[Glen88]

Without using a calculator show that:

tan^-12/3 + tan^-11/5 = pi/4

Had no luck using triangles.

 

[onebytwo]

Without using a calculator show that:

tan^-12/3 + tan^-11/5 = pi/4

Had no luck using triangles.

take the tan of both sides
let A=tan^-1(2/3) and let B=tan^-1(1/5)
then expand tan(A+B)
simplify, then show that it equals tan(pi/4) i.e. 1

EDIT: too slow

 

[Raginsheep]

My only problem with your methods there is that you are assuming the result is true. Just let pi/4=A and solve to find A.