Instructional Video
Art of Problem Solving

Art of Problem Solving: Triangle Inequality Introduction

9th - 10th
Video tutorial uses examples to introduce triangle inequality. [6:15]
Instructional Video
Art of Problem Solving

Art of Problem Solving: Angles in a Polygon Part 2

9th - 10th
Video tutorial uses examples to reinforce understanding of how to find the measure of each angle of a polygon. [9:26]
Instructional Video
Study Pug

Study Pug: Pythagorean Theorem

10th - 12th Standards
In a nutshell, Pythagorean Theorem describes the relationship between the lengths and sides of a right triangle. Watch this video for a detailed explanation along with various examples. [8:48]
Instructional Video
PatrickJMT

Patrick Jmt: Pythagorean Theorem

9th - 10th Standards
Video tutorial defines the Pythagorean theorem and features a few problems using it. [9:04]
Instructional Video
Khan Academy

Khan Academy: Classifying Triangles

3rd - 5th Standards
Learn to categorize triangles as scalene, isosceles, equilateral, acute, right, or obtuse.
Instructional Video
Khan Academy

Khan Academy: Worked Example: Classifying Triangles

3rd - 5th Standards
Work through sample problems categorizing triangles as scalene, isosceles, equilateral, acute, right, or obtuse.
Instructional Video
Khan Academy

Khan Academy: Ordering Triangle Sides and Angles Example

6th - 8th
Sal first solves a problem where he orders the sides of a triangle given the angles, then solves a problem where he orders the angles of a triangle given the sides.
Instructional Video
Khan Academy

Khan Academy: Ca Geometry: Triangles and Parallelograms

9th - 10th Standards
Worked examples of triangles and parallelograms.
Instructional Video
PBS

Pbs Learning Media: Peg + Cat: Geometry Collection

Pre-K - K Standards
This collection includes 16 Peg + Cat video clips about geometry including 2-D and 3-D shapes.
Instructional Video
Sophia Learning

Sophia: Corresponding Parts: Lesson 1

9th - 10th Standards
This lesson [2:00] will define the phrase corresponding parts (e.g. angles, sides, etc.). It is 1 of 5 in the series titled "Corresponding Parts."
Instructional Video
Sophia Learning

Sophia: Finding a Missing Angle: Lesson 2

9th - 10th
This lesson will go over the steps involved in finding the missing angle of a given triangle.
Instructional Video
Sophia Learning

Sophia: Finding the Missing Angle of Right Triangle: Lesson 2

9th - 10th
Following this lesson, the angle measure of one non-right angle of a right triangle, and the right angle symbol in the right angle of the triangle, you'll be able to determine the value of the missing angle. It is 2 of 9 in the series...
Instructional Video
Sophia Learning

Sophia: Finding the Missing Angle of Right Triangle: Lesson 6

9th - 10th
Following this lesson, the angle measure of one non-right angle of a right triangle, and the right angle symbol in the right angle of the triangle, you'll be able to determine the value of the missing angle. It is 6 of 9 in the series...
Instructional Video
Sophia Learning

Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 2

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 2 of 9 in the series titled "Finding the Missing Side of a 45-45-90 Triangle."
Instructional Video
Sophia Learning

Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 3

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 3 of 9 in the series titled "Finding the Missing Side of a 45-45-90 Triangle."
Instructional Video
Sophia Learning

Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 5

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 5 of 9 in the series titled "Finding the Missing Side of a 45-45-90 Triangle."
Instructional Video
Sophia Learning

Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 6

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 6 of 9 in the series titled "Finding the Missing Side of a 45-45-90 Triangle."
Instructional Video
Sophia Learning

Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 9

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 9 of 9 in the series titled "Finding the Missing Side of a 45-45-90 Triangle."
Instructional Video
Sophia Learning

Sophia: Sides of a Triangle: Lesson 4

9th - 10th
This lesson explains the rules for side lengths involved in creating a triangle. It is 4 of 7 in the series titled "Sides of a Triangle."
Instructional Video
Sophia Learning

Sophia: Sides of a Triangle: Lesson 5

9th - 10th
This lesson explains the rules for side lengths involved in creating a triangle. It is 5 of 7 in the series titled "Sides of a Triangle."
Instructional Video
Sophia Learning

Sophia: Sides of a Triangle: Lesson 1

9th - 10th
This lesson explains the rules for side lengths involved in creating a triangle. It is 1 of 7 in the series titled "Sides of a Triangle."
Instructional Video
Sophia Learning

Sophia: Using Similar Triangles to Make Indirect Measurements

9th - 10th Standards
This lesson explains why similar triangles can be used to make indirect measurements, and provides an example.
Instructional Video
Sophia Learning

Sophia: Using the 30 60 90 Rule: Lesson 2

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 2 of 9 in the series titled "Using the 30-60-90 Rule."
Instructional Video
Sophia Learning

Sophia: Using the 30 60 90 Rule: Lesson 3

9th - 10th
In this lesson, you'll learn how to use the lengths of two sides of a triangle and the ratio of the side lengths to find the length of the missing side. It is 3 of 9 in the series titled "Using the 30-60-90 Rule."