Next, draw a triangle consisting of side lengths of the 3, 4, and 5 inches. “How would you classify the largest angle in this triangle?”

How can you verify if a triangle has a right angle, and is therefore, a right triangle? One way to verify that a triangle has a right angle is to use a protractor.

Without forming the triangles again, use your results from your table that DID create triangles, to see if the ones you thought contained right angles, in fact did.

How could you test to see if a triangle is acute or obtuse?

Watch the following video to see how to classify triangles by angles using the side lengths. After watching the video, return to this page by using the back arrow.