Virtual Nerd
Virtual Nerd: What Is the Law of Sines?
The Law of Sines helps with finding a missing side or angle measurement of a triangle. Watch this tutorial to learn about this proportion. [5:57]
Khan Academy
Khan Academy: Geometry: Introduction to Angles (Old)
Defines an angle, complementary angles, supplementary angles, and relates reflex angle measures to degress in a circle. [9:55]
Khan Academy
Khan Academy: Geometry: Complementary and Supplementary Angles
Defines and gives examples of complementary angles, supplementary angles, and adjacent angles. Practice problems available. [8:31]
Khan Academy
Khan Academy: Angles: Complementary and Supplementary Angles
Basics of complementary, supplementary, adjacent and straight angles. Also touching on what it means to be perpendicular.
Khan Academy
Khan Academy: Triangles: Triangle Angle Example 3
Explains how to solve for multiple missing angles in a diagram composed of multiple triangles using the triangle sum theorem and other angle relationships.
Khan Academy
Khan Academy: Trig Identities: Law of Cosines
Introduction to the law of cosines to solve for a side of a triangle when 2 sides and an angle are known.
Khan Academy
Khan Academy: Geometry: Angles (Part 2)
Describes complementary and supplementary angles. Explains how to use properties of complementary and supplementary angles to solve for missing angle measures. Introduces idea that vertical angles (opposite angles) are congruent. [9:05]
Khan Academy
Khan Academy: Angles (Part 2)
Describes complementary and supplementary angles. Explains how to use properties of complementary and supplementary angles to solve for missing angle measures. Introduces idea that vertical angles (opposite angles) are congruent. [9:05]
Khan Academy
Khan Academy: Trig to Solve the Sides and Angles of a Right Triangle
Worked example using trigonometry to solve for the lengths of the sides of a right triangle given one of the non-right angles.
Sophia Learning
Sophia: Properties of Equilateral Triangle and Takin' It 2 the Streets
Use examples to solve for the angles of equilateral triangles in a PowerPoint presentation. Includes video. [4:18]
Khan Academy
Khan Academy: Triangles: Similarity Example Problems
Explains how to identify and use similar triangles in order to determine unknown side lengths in two given diagrams.
Virtual Nerd
Virtual Nerd: Find Missing Angles in an Isosceles Triangle Using Right Triangles
Discover how identifying your triangle first can be very helpful in solving for a missing interior angle measurement. [3:40]
Virtual Nerd
Virtual Nerd: How Do You Identify Corresponding Parts in Congruent Triangles?
Follow along with this tutorial to understand how to identify corresponding sides and angles. [7:31]
PatrickJMT
Patrick Jmt: Law of Cosines, Example 1
Easy to follow video tutorial gives the formula for the Law of Cosines and uses it to find the missing side length of a triangle. [5:05]
Khan Academy
Khan Academy: Angles Formed Between Transversals and Parallel Lines
This video explains the relationship between the measures of angles formed when parallel lines are cut by a transversal.
Khan Academy
Khan Academy: Basic Trigonometric Ratios: Basic Trigonometry Ii
A few more examples using SOH CAH TOA. Examples of finding sine, cosine and tangent for two different right triangles, including finding side lengths by the Pythagorean Theorem and rationalizing the denominator.
Khan Academy
Khan Academy: Triangles: Triangle Angle Example 1
Explains how to use the triangle sum theorem to solve for missing angle measures in a triangle. A little about exterior angles being the sum of the remote interior angles. Also shows the relationship between the measure of an exterior...
Khan Academy
Khan Academy: Angles (Part 3)
Identifies and defines the types of angles formed by parallel lines cut by a transversal and the relationship of their measures.
Khan Academy
Khan Academy: More Trig Examples: 2003 Aime Ii Problem 11
Video demonstrates solving a trigonometric problem that includes finding the area of an oblique triangle using the Pythagorean Theorem and the law of cosines.
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: Geometry: Angles Formed Between Transversals and Parallel Lines
Explains the relationship between the measures of angles formed when parallel lines are cut by a transversal based on relationships of corresponding, vertical, and supplementary angles. [7:53]
Khan Academy
Khan Academy: Geometry: Angles (Part 3)
Identifies and defines the types of angles formed by parallel lines cut by a transversal and the relationship of their measures. Discusses Triangle Sum Theorem. [9:48]
Art of Problem Solving
Art of Problem Solving: Introduction to Angles
Video tutorial uses examples to provide an introduction to angles including right, acute, and obtuse angles. [8:22]