If the two sides of a right triangle are 17 and 15, then the third side is equal …

Since the condition of the assignment does not indicate which specific parties these are, we will consider two options:
Option number 1 (the sides indicated in the condition are legs).
Let us determine what the hypotenuse of our triangle is equal to, if from the condition we know that the legs are 17 and 15:
√ (172 + 152) = √ (289 + 225) = √514.
Answer: The hypotenuse is √514.

Option number 2 (one side is the hypotenuse, the other is the leg).
Let’s determine what the second leg of our triangle will be:
√ (172 – 152) = √ (289 – 225) = √64 = 8.
Answer: The leg is 8.