Student Tutorial: Geometry Basics: Triangle Basics


Learn about triangles. For this tutorial you'll be using the Desmos Geometry Tools, which are free: Watch the video and follow along using the Desmos tools.

Click the arrows on the bottom to get started

Math Clip Art: Student Tutorial Title Page

Triangle Basics Title Card

A triangle is a closed figure with three straight sides.

This is not a closed figure, so this is not a triangle.

This is a closed figure with three sides, but not all sides are straight, so this isn’t a triangle.

A triangle has three sides made up of three line segments.

Triangles can also be formed from rays and lines.

Each endpoint of the segments can be labeled.

Use the labels to define the sides of the triangle.

A triangle consists of three angles.

The endpoints of the segments define the sides and angles.

The endpoints can also be used to label the sides and angles.

The sum of the angles of a triangle is 180°.