This Basic geometry and measurement course is a refresher of length, area, perimeter, volume, angle measure, and transformations of 2D and 3D figures. If you are learning the content for …

Learn high school geometry—transformations, congruence, similarity, trigonometry, analytic geometry, and more (aligned with Common Core standards).

Unit 13: Trigonometry Special right triangles Introduction to the trigonometric ratios Solving for a side in a right triangle using the trigonometric ratios Solving for an angle in a right triangle …

Sal's old angle videos Learn Intro to angles (old) Angles (part 2) Angles (part 3) Angles formed between transversals and parallel lines

Get ready for high school geometry! Learn the skills that will set you up for success in congruence, similarity, and triangle trigonometry; analytic geometry; conic sections; and circles …

Intro to Euclidean geometry Learn Getting ready for performing transformations Euclid as the father of geometry

Learn key geometric terms like colinear points, midpoints, and vertices, and enhance your knowledge of geometry. Improve your skills and discover the world of shapes and space.

Huh... so is there more than one name for these kinds of transformations? Here they're known as "rigid", but my geometry teacher refers to them as "isometric". Is there an actual difference?

Recognizing shapes Classifying triangles Types of triangles review Intro to quadrilaterals Identifying quadrilaterals

We use coordinates to describe where something is. In geometry, coordinates say where points are on a grid we call the "coordinate plane".