Struggling with a Deceptively Difficult Integral

[imranq]

Homework Statement

It looks deceptively easy, but I can't seem to get it...
$$\int^{\frac{\pi}{4}}_{0}{\\sec^4{x}\tan^4{x}}\,dx$$

Homework Equations

$$\sec^2{x} = \tan^2{x} +1$$

The Attempt at a Solution

I've tried, but they all end up as trigonometric polynomials

 

[Dick]

It IS easy. Substitute u=tan(x).

 

[imranq]

ah shoot! Thanks, now I got it