Curated OER
How Do You Find the Height of a Triangle if You Know the Area and Base?
Use the formula for the area of a triangle to find the height of the triangle. If the problem gives the value of the area and the value of the base, then the height can be found using the formula for the area of a triangle. The...
Curated OER
How Do You Use Complementary Angles to Find a Missing Angle?
Are complementary angles nice to each other? That's not what complementary means in math. Complementary angles are two angles that add up to 90 degrees and form a right triangle. So if given one value in a problem about complementary...
Curated OER
What is a Rectangle?
What are the characteristics and properties of a quadrilateral that make it a rectangle? Four sides? Right angles? Parallel sides? Watch this video and follow along as the instructor explains the terms and properties that make a...
Curated OER
What is a Parallelogram?
A rectangle, a rhombus, a square, a trapezoid - are any of these a parallelogram? What are the criteria that make a shape a parallelogram? It has something to do with parallel sides, congruent sides, and congruent angles. Help your young...
Curated OER
How Do You Find a Missing Side of a Right Triangle Using Sine?
What's a trigonometric ratio? It is a ratio between two sides of a right triangle. In this problem, find sin(A) in the given right triangle. Use the ratio of the opposite side divided by the hypotenuse to find sin(A). The instructor...
Khan Academy
Khan Academy: Geometry: Measuring Angles in Degrees
Explains how to measure an angle in degrees using a protractor. Defines acute, right, and obtuse angles. Practice problems available. [8:22]
Khan Academy
Khan Academy: Geometry: Acute, Obtuse, and Right Angles
Demonstrates how to find all acute, obtuse, and right angles in a given diagram. [6:35]
Virtual Nerd
Virtual Nerd: How Do You Find a Missing Side of a Right Triangle Using Sine?
The sine ratio is not only used to identify a ratio between two sides of a right triangle, but it can also be used to find a missing side length. This tutorial shows you how to use the sine ratio to find that missing measurement. [4:29]
Virtual Nerd
Virtual Nerd: What Are Perpendicular Lines?
The angles formed by perpendicular lines will always be the same. Take a look at this tutorial to learn about perpendicular lines and see a special trick involving them. [5:22]
Virtual Nerd
Virtual Nerd: What Are Complementary Angles?
Complementary angles always add up to 90 degrees. Watch this tutorial to learn about complementary angles and see how to use this knowledge to solve a problem involving these special types of angles. [3:20]
Khan Academy
Khan Academy: Measuring Angles in Degrees
Explains what a protractor is and how it is used to measure the size of angles. Also discusses the different types of angles. [8:23]
CK-12 Foundation
Ck 12: Elem Math: Overview of Classification of Angles
[Free Registration/Login may be required to access all resource tools.] Video describing four types of angles - right, acute, obtuse and straight. [1:19]
Virtual Nerd
Virtual Nerd: What Is a Tangent Line to a Circle?
For a line to be tangent, it must have a special relationship with a circle. It can only intersect the circle at one point. Watch this tutorial for a better understanding. [3:01]
Sophia Learning
Sophia: Classifying Triangles
This video lesson describes and provides examples of right, acute, and obtuse triangles. Students can check their understanding with an assessment. [2:24]
Sophia Learning
Sophia: Slant Height of a Pyramid
This video lesson demonstrates how to use the Pythagorean Theorem to find the slant height of pyramid.
Virtual Nerd
Virtual Nerd: How Do You Find the Cosine of an Angle in a Right Triangle?
A trigonometric ratio is a ratio between two sides of a right triangle. The cosine ratio is one of these ratios. Take a look at this tutorial to see how to find the cosine of a particular angle in a right triangle. [3:22]
Sophia Learning
Sophia: Right Angle: Lesson 10
This lesson defines the phrase right angle. It is 10 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 11
This lesson defines the phrase right angle. It is 11 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 12
This lesson defines the phrase right angle. It is 12 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 13
This lesson defines the phrase right angle. It is 13 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 9
This lesson defines the phrase right angle. It is 9 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 2
This lesson defines the phrase right angle. It is 2 of 14 in the series titled "Right Angle."
Sophia Learning
Sophia: Right Angle: Lesson 3
This lesson defines the phrase right angle. It is 3 of 14 in the series titled "Right Angle."
Khan Academy
Khan Academy: Recognizing Angles
Demonstrates how to solve problems that ask you to identify types of angles. [2:15]