You can tell when you cant draw an even L shaped figure at the intersects of the bottom and the side. 90 degrees. But there are many different ways that may make more sense. Happy to help:)
So a right triangle is classified as a right triangle because it has one right angle. You can tell if it's not a right triangle by the angle measurements. If all the angles are above or below 90 degrees, it's not a right triangle. If one of the angles is 90 degrees, it's classified as a right triangle.
