You can use the Pythagorean Theorem: a² + b² = c²
Also remember that the longest side of the triangle is the hypotenuse, whereas the smaller sides are the legs.
One way to solve this equation, you need to start by filling in a² + b² = c² with the numbers you are given. So you will have 72² + b² = 75². Whatever "b" is should equal 75².
Since 72² = 5184 and 75² = 5625, you can subtract and find the squared value of the number you need.
So, 5625 - 5184 = 441. Find the square root and you will have "x".
The square root of 441 is 21, meaning THE ANSWER IS: x = 21²
Another way to solve the equation is to use the smaller triangle. You can find common variables in order to find "x".
In this case, the common variable would be 3. You can just divide the larger legs by the smaller ones, or the larger hypotenuses by the smaller one.
For example: 72/24 = 3 AND 72/3 = 24 AND 24 x 3 = 72 (just so you can see different ways to look at it/find the answer).
Since, 7 x 3 = 21, THE ANSWER IS: x = 21².
Don't forget that it is squared!!
Hopefully this explanation was clear. I wanted to give you two ways to solve it to help you get the answer in the future. I put where the answer was in all caps to help make it clearer. Hope this helps! :)
