Below tutorials are from Khan Academy –
Learn what lines, line segments, and rays are and how to use them.
In this topic, we will learn what an angle is and how to label, measure and construct them. We will also explore special types of angles.
Classify shapes and solve problems using what we know of the properties of shapes.
You probably like triangles. You think they are useful. They show up a lot. What you’ll see in this topic is that they are far more magical and mystical than you ever imagined!
Quadrilaterals only have one side more than triangles, but this opens up an entire new world with a huge variety of quadrilateral types. Learn about it here.
We use coordinates to describe where something is. In geometry, coordinates say where points are on a grid we call the “coordinate plane”.
Area and perimeter
Area and perimeter help us measure the size of 2D shapes. We’ll start with the area and perimeter of rectangles. From there, we’ll tackle trickier shapes, such as triangles and circles.
Volume and surface area
Volume and surface area help us measure the size of 3D objects. We’ll start with the volume and surface area of rectangular prisms. From there, we’ll tackle trickier objects, such as cones and spheres.
The Pythagorean theorem describes a special relationship between the sides of a right triangle. Even the ancients knew of this relationship. In this topic, we’ll figure out how to use the Pythagorean theorem and prove why it works.
In this topic you will learn about the most useful math concept for creating video game graphics: geometric transformations, specifically translations, rotations, reflections, and dilations. You will learn how to perform the transformations, and how to map one figure into another using these transformations.
Learn what it means for two figures to be congruent, and how to determine whether two figures are congruent or not. Use this immensely important concept to prove various geometric theorems about triangles and parallelograms.
Learn what it means for two figures to be similar, and how to determine whether two figures are similar or not. Use this concept to prove geometric theorems and solve some problems with polygons.
Triangles are not always right (although they are never wrong), but when they are it opens up an exciting world of possibilities. Not only are right triangles cool in their own right (pun intended), they are the basis of very important ideas in analytic geometry (the distance between two points in space) and trigonometry.
Explore, prove, and apply important properties of circles that have to do with things like arc length, radians, inscribed angles, and tangents.
In analytic geometry, also known as coordinate geometry, we think about geometric objects on the coordinate plane. For example, we can see that opposite sides of a parallelogram are parallel by by writing a linear equation for each side and seeing that the slopes are the same.