# Homework Help: Trig Substitution

1. Feb 23, 2010

### bfpri

http://img708.imageshack.us/img708/8897/symimage.gif [Broken]

so I did x=atanΘ. which is x=3tanΘ and dx is $$3sec^2\Theta$$. Then it is

$$\sqrt[]{9tan^2\Theta+9}$$*$$3sec^2\Theta$$ which evaluates after factoring to $$\sqrt[]{9sec^2\Theta}$$*$$3sec^2\Theta$$ which is then $$3sec\Theta*3sec^2\Theta$$ If i take the 9 out of the integral, that leaves $$sec^3\Theta$$. And i'm stuck

Last edited by a moderator: May 4, 2017
2. Feb 23, 2010