# Homework Help: Proof about primes

1. Jul 17, 2013

### cragar

1. The problem statement, all variables and given/known data
Prove that every prime of the form 4k+1 is a hypotenuse of a rectangular triangle with integer sides.
3. The attempt at a solution
I tried messing around with the Pythagorean theorem but not really sure where to go.
$x^2+y^2=(4k+1)^2$
it seems like there would exist x and y that make that true, but I haven't really said anything about the primes

2. Jul 17, 2013