You can put this solution on YOUR website! Since we have a triangle with legs of 5 , x(our unknown side) and a hypotenuse of 10, we can use Pythagoreans theorem to find the unknown side.
Pythagoreans theorem
Plug in a=5 and c=10 and lets solve for b
Square each individual term
Subtract 25 from both sides
Combine like terms
Take the square root of both sides
Simplify
Factor 75 into 25*3
Break up the square roots using the identity
Take the square root of the perfect square 25 to get 5