Khan Academy
Khan Academy: Triangles: Similar Triangle Example Problems
Demonstration on how to determine if triangles are similar based on AA, SSS, or SAS similarity postulates.
Khan Academy
Khan Academy: Triangles: Congruent Triangles and Sss
This video tutorial explains how to use triangle congruence to identify measures of corresponding sides and angles in triangles. Defines side-side-side (SSS) postulate.
Khan Academy
Khan Academy: Triangles: Triangle Angle Example 2
Shows how to find the measure of missing angles using the triangle sum theorem and vertical angles.
Khan Academy
Khan Academy: Triangles: Pythagorean Theorem Proof Using Similarity
This video shows a proof for the Pythagorean Theorem by breaking a right triangle into two similar triangles and setting up ratios of corresponding sides.
Khan Academy
Khan Academy: Triangles: Pythagorean Theorem Ii
More Pythagorean Theorem examples. Introduction to 45-45-90 triangles.
Khan Academy
Khan Academy: Basic Triangle Proofs Module Example 2
A video proving that the given triangles are congruent by ASA.
Art of Problem Solving
Art of Problem Solving: Triangle Inequality Introduction
Video tutorial uses examples to introduce triangle inequality. [6:15]
Art of Problem Solving
Art of Problem Solving: Angles in a Polygon Part 2
Video tutorial uses examples to reinforce understanding of how to find the measure of each angle of a polygon. [9:26]
Study Pug
Study Pug: Pythagorean Theorem
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]
PatrickJMT
Patrick Jmt: Pythagorean Theorem
Video tutorial defines the Pythagorean theorem and features a few problems using it. [9:04]
Khan Academy
Khan Academy: Classifying Triangles
Learn to categorize triangles as scalene, isosceles, equilateral, acute, right, or obtuse.
Khan Academy
Khan Academy: Worked Example: Classifying Triangles
Work through sample problems categorizing triangles as scalene, isosceles, equilateral, acute, right, or obtuse.
Khan Academy
Khan Academy: Ordering Triangle Sides and Angles Example
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.
Khan Academy
Khan Academy: Ca Geometry: Triangles and Parallelograms
Worked examples of triangles and parallelograms.
PBS
Pbs Learning Media: Peg + Cat: Geometry Collection
This collection includes 16 Peg + Cat video clips about geometry including 2-D and 3-D shapes.
Sophia Learning
Sophia: Corresponding Parts: Lesson 1
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."
Sophia Learning
Sophia: Finding a Missing Angle: Lesson 2
This lesson will go over the steps involved in finding the missing angle of a given triangle.
Sophia Learning
Sophia: Finding the Missing Angle of Right Triangle: Lesson 2
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...
Sophia Learning
Sophia: Finding the Missing Angle of Right Triangle: Lesson 6
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...
Sophia Learning
Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 2
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."
Sophia Learning
Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 3
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."
Sophia Learning
Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 5
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."
Sophia Learning
Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 6
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."
Sophia Learning
Sophia: Finding the Missing Side of a 45 45 90 Triangle: Lesson 9
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."