Shoshanna says that a triangle with side lengths 17m,8m and 15m is not a right triangle because 17 squared plus 8 squared equals 353, 15 squared equals 225, and 353 does not equal 225. is she correct? explain.

Shoshanna is not correct
to find if a right triangle is actually a right triangle you have to do the two smaller values squared equals the larger value squared
(a²+b²=c²)

correct way to solve this problem:
a²+b²=c²
8²+15²+17²
64+225=289
289=289
so, this triangle is a right triangle

I would use substitute and keep going from there