1. The problem statement, all variables and given/known data If C^2 = ab and the greatest common divisor of a and b is equal to 1, prove that a and b are perfect squares 2. Relevant equations I know that if (a,b)=1, then there exists integers u and v where 1=au+bv (even though i don't think this is necessary in this proof) also, I know that the square root of a perfect square is a rational number, if it is not a perfect square, then it is irrational Lastly, I know that since (a,b)=1 that means a and b are relatively prime 3. The attempt at a solution I have absolutely no idea how to do this proof. I know i need to show that the square root of a and the square root of b are rational, but I don't know how to do that. Maybe I could do it by trying to show it is irrational and finding a contradiction? Any help would be great!