Question

A triangle has side lengths of 10, 15, and 7. Is the triangle acute, obtuse or right? Explain.

Answer 1

c^2 = a^2 + b^2
15^2 = 7^2 + 10^2
225 = 49 + 100
225 > 149
Since c^2 > a^2 + b^2, it is obtuse.
Here are the rules:
c^2 = a^2 + b^2: Right Triangle
c^2 > a^2 + b^2: Obtuse Triangle
c^2 < a^2 + b^2 Acute Triangle