Let's do an exercise together in which we identify parallel and perpendicular lines. This is great practice.

Learn how to prove the ratios between the sides of a 30-60-90 triangle.

Learn how to determining the midpoint of a line segment algebraically.

We're matching the visual angle with the corresponding angle measure. See if you do it on your own before listening to Sal!

This module explains an elegant visual proof of the Pythagorean Theorem developed by the 12th century Indian mathematician Bhaskara.

This problem asks you to solve for an unknown supplementary angle.

Solve for a mystery angle when you know the adjacent angle, and what the combination of the mystery angle and the adjacent angle is.

This module demonstrates how to use the Pythagorean Theorem to solve for an unknown side of a right triangle.

Solve this interesting problem to find the sums of particular exterior angles of an irregular pentagon.

This module explains the axis of symmetry and how to find it, using heptagons (7-sided polygons) as an example.