This is just some pythagorean theorem, or a^2 + b^2 = c^2. We have a and b, which is 9 and 12, and we need to find c. To find c, we need to first square those, giving u 81 and 144. Now, we need to add them, giving us 225, meaning c^2 = 225. However, we need to find c on its own, so we have to find the square root of 225. That would be 15.
A geometric figure enclosed by a circle is called an inscribed figure.
Instead use WolframAlpha.com for math questions I would paste the answer but a cretinous fop has "disabled" that feature by javascript -- which is trivial to circumvent but I won't bother with the time.
The second one is the only equivalent equation. Simply plug in each variable in each equation. And compare!
