9514 1404 393
Answer:
13
Step-by-step explanation:
The hypotenuse can be found using the Pythagorean theorem. If we call that side 'c', then the theorem tells us ...
c² = 5² + 12²
c² = 25 +144 = 169
c = √169 = 13
The length of the third side is 13 units.
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Additional comment
The numbers (5, 12, 13) are what is called a "Pythagorean triple." That is, they are integers that can be used to form a right triangle. Others often seen in algebra problems are the (3, 4, 5), (7, 24, 25), and (8, 15, 17) triples. It can be worth your trouble to remember these. Then when you see side lengths of 5 and 12, you don't need to do any math to know the third side is 13.
