Basic Geometry
Get up to speed on the core foundations of geometry.
Content

6. Volume and surface area
7. The Pythagorean theorem 8. Transformations, congruence, and similarity 
1. Lines
2. Angles
Angle basicsInterpreting anglesRelationships between angles 
3. Shapes
4. The coordinate plane
5. Area and perimeter
6. Volume and surface area
7. The Pythagorean theorem
8. Transformations, congruence, and similarity
Transformations
Congruence and similarity
Geometry
Content

08. Right triangles and trigonometry
09. Circles 10. Perimeter, area, and volume 11. Analytic geometry 12. Geometric constructions 13. Miscellaneous 
1. Tools of geometry
3. Special properties and parts of triangles
4. Quadrilaterals
5. Transformations
6. Congruence
7. Similarity
8. Right triangles and trigonometry
9. Circles
Properties of tangentsArea of inscribed triangleStandard equation of a circleExpanded equation of a circle 
10. Perimeter, area, and volume
11. Analytic geometry
Coordinate plane proofsProve properties of shapes by putting them on the coordinate plane and then using distances, midpoints, and slopes.
Equation of a circleYou know that a circle can be viewed as the set of all points that whose distance from the center is equal to the radius. In this tutorial, we use this information and the Pythagorean Theorem to derive the equation of a circle.
Challenge: Distance between a point and a lineAn optional tutorial where you'll figure out the minimum distance from a point to a given line.

12. Geometric constructions
We now have fancy computers to help us perfectly draw things, but have you ever wondered how people drew perfect circles or angle bisectors or perpendicular bisectors back in the day. Well this tutorial will have you doing just as your grandparents did (actually, a little different since you'll still be using a computer to draw circles and lines with a virtual compass and straightedge).
Constructing bisectors of lines and anglesWith just a compass and a straightedge (or virtual versions of them), you'll be amazed by how many geometric shapes you can construct perfectly. This tutorial gets you started with the building block of how to bisect angle and lines (and how to construct perpendicular bisectors of lines).

Constructing regular polygons inscribed in circlesHave you ever wondered how people would draw a square, equilateral triangle or even hexagon before there were computers? Well, now you're going to do just that (ironically, with a computer). Using our virtual compass and straightedge, you'll construct several regular shapes (by inscribing them inside circles).
Constructing circumcircles and incirclesIn our study of triangles, we spent a decent amount of time think about incenters (the intersections of the angle bisectors) and circumcenters (the intersections of the perpendicular bisectors). We'll now leverage this knowledge to actually construct circle inscribed and circumscribed about a triangle using only a compass and straightedge (actually virtual versions of them).
Constructing a line tangent to a circle

13. Miscellaneous
Worked examplesSal does the 80 problems from the released questions from the California Standards Test for Geometry. Basic understanding of Algebra I necessary.
