Khan Academy
Khan Academy: Geometry: Inradius Perimeter and Area
Proof that the area of a triangle is equal to half the inradius times the perimeter of the triangle, or the area is equal to the inradius times the semiperimeter. This video also appears in the Geometry: Circles strand. [7:29]
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]
Khan Academy
Khan Academy: Geometry: Area and Perimeter
Explains how to calculate the area of rectangles, squares, and triangles, in addition to the perimeter of rectangles and squares. Practice problems available. [12:20]
Virtual Nerd
Virtual Nerd: Find the Height of a Triangle if You Know the Area and Base
Take a look at this tutorial to learn how to use the formula for the area of a triangle to find the height if you already know the area and the length of the base. [6:09]
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]
Math Playground
Math Playground: How Do You Find the Area of a Triangle?
This video [3:54] illustrates how to calculate the area of a triangle and explains the logic behind the formula.
Khan Academy
Khan Academy: Area of Triangles Intuition
Learn the formula for the area of a triangle, one half base times height. [5:29]
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: Triangle Area Proofs
A video proving that the area of any triangle is half the product of the base and the height.
Sophia Learning
Sophia: Calculating the Area of a Triangle
Use different size triangle to determine how to solve for the area in this video lesson. Take quiz to check understanding. [3:41]
Sophia Learning
Sophia: Calculating the Area of a Triangle
This video lesson demonstrates how to calculate the area of a triangle. It includes detailed examples including ones that use the Pythagorean Theorem. Students can check their understanding with an assessment. [10:43]
Sophia Learning
Sophia: Calculating the Perimeter of a Triangle
This video lesson demonstrates how to find the perimeter of triangles. [3:42] The tutorial includes detailed examples. Students can check their understanding with an assessment.
Sophia Learning
Sophia: Calculating the Perimeter of a Triangle
Solve for the perimeter of different triangles and take a quiz. [3:41]
Khan Academy
Khan Academy: Geometry: Part 1 of Proof of Heron's Formula
Demonstrates how to derive a version of Heron's formula using the Pythagorean Theorem and the formula for the area of a triangle. Applies Heron's formula to solve a sample problem. [10:59]
Khan Academy
Khan Academy: Geometry: Part 2 of the Proof of Heron's Formula
Completes the proof of Heron's formula that was begun in the video, "Part 1 of Proof of Heron's Formula." [12:08]
Khan Academy
Khan Academy: Triangles: Area of an Equilateral Triangle
This video tutorial explores finding the formula for the area of an equilateral triangle with side length of s.
Art of Problem Solving
Art of Problem Solving: Areas of Rectangles and Right Triangles
Video tutorial introduces the area of a rectangle and discovers a formula for the area of a right triangle. [4:44]
Khan Academy
Khan Academy: Area of Triangle Proof
Proof that shows that the area of any triangle is 1/2 b x h.
Khan Academy
Khan Academy: Area of Equilateral Triangle (Advanced)
Sal finds a shaded area defined by two equilateral triangles whose side lengths are given.
Khan Academy
Khan Academy: Area of Diagonal Generated Triangles
Watch Sal prove that the areas of the pairs of triangles generated by the diagonals of a rectangle are equal.
Khan Academy
Khan Academy: Area of Equilateral Triangle
Finding the formula for the area of an equilateral triangle with side s.
Sophia Learning
Sophia: Finding the Area of an Sas Triangle: Lesson 4
Finding the are of an SAS triangle is demonstrated in this lesson. It is 4 of 7 in the series titled "Finding the Area of an SAS Triangle."
Sophia Learning
Sophia: Finding the Area of an Sas Triangle: Lesson 6
Finding the are of an SAS triangle is demonstrated in this lesson. It is 6 of 7 in the series titled "Finding the Area of an SAS Triangle."
Sophia Learning
Sophia: Finding the Area of an Sas Triangle: Lesson 1
Finding the are of an SAS triangle is demonstrated in this lesson. It is 1 of 7 in the series titled "Finding the Area of an SAS Triangle."