The answer is 15 because to the the lenght of the missing number you have to use the Pythagorean Theorem.So first you have to use c^2=a^2 +b^2.
25^2=20^2 + b^2 then 625=400 + b^2. 625-400= 225. So what equals 225. The answer is 15. Hope this helps
<span>If it's 3ft on each side, the glass is a square.
The area for square is;
A=s</span>²
where
<span> A=(3)</span>²
<span>
so the area is 9ft</span>²
