# Trig integral

The question is to evaluate the integral in the attachment.

Using trig substition, I've reduced it to ∫ (tanz)^2 where z will be found using the triangle. I just need to integrate tangent squared which I can't seem to figure how to do. I tried using the trig identity (secx)^2 - 1 but I don't know what to do after.

#### Attachments

• integral.png
886 bytes · Views: 303

arildno
Homework Helper
Gold Member
Dearly Missed
That is a good move.

Hint:
What do you get if you differentiate tan(z)?

I get (sec(z))^2)

arildno
Homework Helper
Gold Member
Dearly Missed
That is to integrate tan, I said differentiate it!

Yes, sorry I realized I had made a mistake so when I differentiate tan, I get sec^2 ...

arildno