Why was the obtuse angle upset? Because it was never right! A valuable resource is loaded with background information on types of angles and lines. Learners review the characteristics of parallel, perpendicular, and...

Geometry is full of shapes, figures, and corresponding things here and there. The guide shares all of the key pieces of geometric information in a nicely color-coded and labeled sheet. 

After reviewing characteristics of seven types of triangles, young geometers discover how to find the missing angle of a triangle. Then, they practice identifying triangles, find missing angles, and find missing side lengths of...

Investigate how similar and congruent figures compare. Learners understand congruent figures have congruent sides and angles, but similar figures only have congruent angles — their sides are proportional. After learning the...

Geometry could be called the study of figures. An overview of the figures found in a typical geometry course contains a study of different triangles, quadrilaterals, and regular polygons. 

There isn't a more popular geometry formula than the Pythagorean Theorem! Learners understand the special side relationships in a right triangle. They use the Pythagorean Theorem to find missing sides and to solve problems. They begin...

This study guide on angles covers key vocabulary, ways to name angles, how to measure them, the Protractor Postulate and the Angle Addition Postulate, types of angles, congruent angles, angle bisectors, and angle pairs. It is available...

A comprehensive guide for learning all about angles with definitions, examples, and practice questions.

Explains the terms and symbols used to discuss line angles, what an angle is, and the types of angles. Includes short video lesson demonstrating how to use a protractor to measure an angle. [0:57]

This study guide on arcs and angles covers key vocabulary, arc measurement in degrees and radians, congruent arcs, bisecting arcs, and the angles on, inside, and outside a circle. Also covers formulas and theorems. It is available for...

This site explains what the measure of the sum of exterior angles is for any polygon, and shows how to find the measure of individual exterior angles for regular polygons with a drawn example.

A "convention" is "just the way a thing is done!". This reference material lists some common conventions (notational assumptions) for geometry and trigonometry.