Sum of interior angles of a triangle

Introduction

Have you ever noticed that no matter how a triangle looks, its angles always seem to “fit” perfectly together? This idea is called the angle sum property of a triangle. It tells us that the three interior angles always add up to 180°. This is useful in solving geome...

Sam added all the interior angles of some triangles from his book. And surprisingly, all sum to 180 degrees, no matter how tall, wide, or small they are.

His teacher explained that this is called the Angle Sum Property of a triangle.

To understand why, imagine triangle ABC. Now, draw a straight line through vertex A that is parallel ...