# Solving a Trig Inverse.

1. Nov 29, 2008

### JoshB645

1. The problem statement, all variables and given/known data
Solve arctan 3x + arctan 2x= pie/4?

2. Relevant equations

3. The attempt at a solution

2. Nov 29, 2008

### soandos

there is a trig identiy that helps.

arctan[x]+arctan[y] = arctan[(x+y)/(1-xy)]

then it is just the angle that has a tan of pi/4 (i am assuming radians), so 1

then solving 5x/(1-6x^2)=1 we get x= 1/6 and x=-1
reject the -1 as the domain of arctan does not include it if is re-inserted into the fuction.