FuseSchool
Area of a Triangle 1/2absinC
Can you find the area of a triangle without knowing the height? Applying trigonometry makes quick work of this type of problem. The video instructor presents problems for scholars to consider and then provides a worked out solution. She...
FuseSchool
Area of a Triangle 1/2absinC Proof
Demonstrate the derivation of the trigonometric area formula for a triangle. Using the base/height formula and the sine ratio, the lesson instructor demonstrates how to combine the two and create the formula A = 1/2absinC. The video...
Mathematics Assessment Project
Modeling Motion: Rolling Cups
Connect the size of a rolling cup to the size of circle it makes. Pupils view videos of cups of different sizes rolling in a circle. Using the videos and additional data, they attempt to determine a relationship between cup...
Corbett Maths
Area of a Triangle – Sine/Trigonometry
Half the base times height was great for elementary school, but now we have a more general formula. Scholars watch a short video that highlights the area formula A = 1/2 ab sin C. The narrator works through an example of applying the...
Khan Academy
Khan Academy: Geometry: Incenter and Incircles of a Triangle
Explains that the intersection of the three angle bisectors of a triangle form the incenter of the triangle. [7:58]
Khan Academy
Khan Academy: Geometry: Finding Area Using Similarity and Congruence
Explains how to determine the area of a pentagonal shaded region in a triangle. The triangle that is broken into multiple similar and congruent triangles. [10:07]
Khan Academy
Khan Academy: Geometry: Triangle Area Proofs
Proof that the area of any triangle is half the product of the base and the height. Three different types of triangles are used to prove the formula. [10:23]
Math Planet
Math Planet: Geometry: Triangles
Discussion of triangles through the use of examples and a video lesson. [1:08]
Sophia Learning
Sophia: Equilateral Triangles: Lesson 2
This lesson will prepare you to distinguish an equilateral triangle based on the sides of a triangle. It is 2 of 8 in the series titled "Equilateral Triangles."
Sophia Learning
Sophia: Equilateral Triangles: Lesson 4
This lesson will prepare you to distinguish an equilateral triangle based on the sides of a triangle. It is 4 of 8 in the series titled "Equilateral Triangles."
Virtual Nerd
Virtual Nerd: What Is the Formula for the Area of a Triangle?
You can find the area of a triangle by using the same formula for the area of a parallelogram. Watch this tutorial to see how it's done. [4:44]
Virtual Nerd
Virtual Nerd: What Is a Triangle?
This tutorial explains triangles and their different types. [5:58]
Virtual Nerd
Virtual Nerd: How Do You Classify Triangles?
If you know what kind of triangle you're looking at, it's much easier to figure out how to solve for various sides and angles. Use this tutorial to practice classifying triangles. [7:15]
Virtual Nerd
Virtual Nerd: How Do You Find the Area of a Triangle?
If you know the length of the base and the height of a triangle, it's easy to find the area. This tutorial illustrates how to plug the numbers into the formula for the area of a triangle and solve. [3:44]
Khan Academy
Khan Academy: Triangles: Finding Area Using Similarity and Congruence
Explains how to determine the area of a pentagonal shaded region in a triangle. The triangle that is broken into multiple similar and congruent triangles.
Khan Academy
Khan Academy: Similarity Example Where Same Side Plays Different Roles
Explains how to determine unknown side lengths in a diagram that involves similar triangles where the two triangles share a side and the shared side corresponds to two different sides in each triangle.
Khan Academy
Khan Academy: Triangles: Triangle Area Proofs
A video proving that the area of any triangle is half the product of the base and the height.
Khan Academy
Khan Academy: Perpendicular Bisectors: Area Circumradius Formula Proof
Proof of the formula relating the area of a triangle to its circumradius.
Virtual Nerd
Virtual Nerd: What Is the Formula for the Area of a Triangle Using Sines?
Learn how to use sines to find the area of a triangle. [5:33]
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.
Khan Academy
Khan Academy: Triangles: Median Centroid Right Triangle Example
This video demonstrates how to find various measures of triangles formed by the medians of a right triangle.
Khan Academy
Khan Academy: Triangles: Review of Triangle Properties
Provides a review of perpendicular bisectors, angle bisectors, medians, and altitudes and the special points of concurrency formed by these parts of a triangle.
Khan Academy
Khan Academy: Triangles: Medians Divide Into Smaller Triangles of Equal Area
Showing that the three medians of a triangle divide it into six smaller triangles of equal area. Also a brief discussion of the centroid is given.
Art of Problem Solving
Art of Problem Solving: Area of an Acute Triangle
Video tutorial uses examples to reinforce understanding of how to find the area of an acute triangle. [8:21]