Instructional Video
Sophia Learning

Sophia: Scalene, Isosceles, and Equilateral Triangles

6th - 8th
Explore scalene, isosceles, and equilateral triangles and how to determine which is which. Assess learning with a quiz.
Instructional Video
Sophia Learning

Sophia: Scalene, Isosceles, and Equilateral Triangle

6th - 8th
Explore types of triangles including scalene, isosceles, and equilateral in this video tutorial. [3:47] Quiz to follow to check understanding.
Instructional Video
Sophia Learning

Sophia: Scalene, Isosceles, and Equilateral Triangles

9th - 10th
This video lesson [2:10] shows examples for classifying triangles by their side lengths. Students can check their understanding with an assessment.
Instructional Video
Sophia Learning

Sophia: Solving for Unknown Sides of Similar Triangles

9th - 10th
Solve for unknown sides of similar triangles and take a quiz to assess learning.
Instructional Video
Math Mammoth

Math Mammoth: Acute, Obtuse, and Right Triangles

3rd - 4th Standards
This lesson goes over the types of triangles. [7:02]
Instructional Video
Khan Academy

Khan Academy: Triangles: Another Isosceles Example Problem

9th - 10th
Review possible angles for an isosceles triangle in this short video.
Instructional Video
Khan Academy

Khan Academy: Classifying Triangles by Angles

3rd - 5th Standards
You say you can't categorize a triangle because you don't know the length of the sides. Guess what? If you know the size of the angles you can!
Instructional Video
Sophia Learning

Sophia: Equilateral Triangle Interior Angles Practice Problems: Lesson 4

9th - 10th
This lesson will provide practice problems that involve solving for unknown angle and side measures of equilateral triangles. It is 4 of 5 in the series titled "Equilateral Triangle Interior Angles Practice Problems."
Instructional Video
Sophia Learning

Sophia: Solve for an Angle of an Isosceles Triangle: Lesson 3

6th - 9th
Given the value of one angle in an isosceles triangle in this lesson, you'll be able to solve for the value of either one of the missing angles, as long as you know which two interior angles are congruent. It is 3 of 12 in the series...
Instructional Video
Sophia Learning

Sophia: Solve for an Angle of an Isosceles Triangle: Lesson 8

9th - 10th
Given the value of one angle in an isosceles triangle in this lesson, you'll be able to solve for the value of either one of the missing angles, as long as you know which two interior angles are congruent. It is 8 of 12 in the series...
Instructional Video
Sophia Learning

Sophia: Solve for an Angle of an Isosceles Triangle: Lesson 1

6th - 9th
Given the value of one angle in an isosceles triangle in this lesson, you'll be able to solve for the value of either one of the missing angles, as long as you know which two interior angles are congruent. It is 1 of 12 in the series...
Instructional Video
Sophia Learning

Sophia: Triangle Angle Combinations: Lesson 4

7th - 8th
This lesson explains how you can have 3 acute angles, 1 obtuse and 2 acute angles or 1 right and 2 acute angles in a triangle. It is 4 of 7 in the series titled "Triangle Angle Combinations."
Instructional Video
Sophia Learning

Sophia: Triangle Angle Combinations: Lesson 1

7th - 8th
This lesson explains how you can have 3 acute angles, 1 obtuse and 2 acute angles or 1 right and 2 acute angles in a triangle. It is 1 of 7 in the series titled "Triangle Angle Combinations."
Instructional Video
Sophia Learning

Sophia: Triangle Notation: Lesson 5

9th - 10th
Following this lesson, you'll be able to name a triangle based on the three vertices and the triangle symbol. It is 5 of 6 in the series titled "Triangle Notation."
Instructional Video
Sophia Learning

Sophia: Triangle Notation: Lesson 1

9th - 10th
Following this lesson, you'll be able to name a triangle based on the three vertices and the triangle symbol. It is 1 of 6 in the series titled "Triangle Notation."
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: Equilateral Triangle Interior Angles Practice Problems: Lesson 2

9th - 10th Standards
This lesson will provide practice problems that involve solving for unknown angle and side measures of equilateral triangles. It is 2 of 5 in the series titled "Equilateral Triangle Interior Angles Practice Problems."
Instructional Video
Sophia Learning

Sophia: Equilateral Triangle Interior Angles Practice Problems: Lesson 3

9th - 10th Standards
This lesson will provide practice problems that involve solving for unknown angle and side measures of equilateral triangles. It is 3 of 5 in the series titled "Equilateral Triangle Interior Angles Practice Problems."
Instructional Video
Sophia Learning

Sophia: Solve for an Angle of an Isosceles Triangle: Lesson 6

9th - 10th
Given the value of one angle in an isosceles triangle in this lesson, you'll be able to solve for the value of either one of the missing angles, as long as you know which two interior angles are congruent. It is 6 of 12 in the series...
Instructional Video
Sophia Learning

Sophia: Triangle Notation: Lesson 2

9th - 10th Standards
Following this lesson, you'll be able to name a triangle based on the three vertices and the triangle symbol. It is 2 of 6 in the series titled "Triangle Notation."
Instructional Video
Shmoop University

Shmoop: Triangles

4th - 8th Standards
A video clip [2:09] using an everyday bag of chips to explain the different types of triangles.