okay so for the first one use the pythagorean theorem. 5^2 x 2^2 so simplify that rq. 25 x 4. so now solve that and c=100 which we need to get the square root of. so that would be 10 so c=10
then for the next one the square root of 8 squared is just 8 and 4^2 is 16. so now the equation for that is 8 +y^2= 16 so simplify that and the solution for that is 2√2