Question

is triangle ABC a right triangle? Why or why not?

Answer 1

No, because a right angle is shaped like an L, is exactly 90 degrees, and usually has a box in the middle where the right angle is :)

Answer 2

Try the Pythagorean theorem.

Answer 3

If the triangle is a right triangle, then the hypotenuse is the longest side.
In this triangle, which side is longest?