Answer:
x=9m
Explanation:
We can use the Pythagorean Theorem formula:
a²+b²=c²
c is the biggest side. In this case we can see that c equals 15. I like to think that b is the second-longest side. In this case that would be 12. So, we can create the equation:
c²-b²=a²
Substitute in the numbers we know:
15²-12²=a²
Simplify:
225-144=a²
81=a²
√81=a
9=a, or x=9m
Note: 9, 12, 15 is a Pythagorean Triple. Remember this triple in the future so you don't have to do more work!
:)