The Easy Formula for How to find Area of a Triangle

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The Simple Guide for Finding Area of a Triangle

A triangle is a 2-D three sided figure that has three angles. The three angles of a triangle always add up to 180 degrees. In order to find the Area of a Triangle, you have to multiply the length of the base by the length of the height and then divide by two. Finding the Area of a Triangle follows the same formula as finding the area of a rectangle except you have to divide by two after you multiply the base and height together. Typically, you will see a dotted line in a triangle that represents the height.

Common Core Standard: 6.G.1

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Here’s how to calculate Area of a Triangle

A triangle is a 2-D three sided shape that has three interior angles. The three interior angles of a triangle always have a sum of 180 degrees. You must multiply the length of the base by the height of the triangle and then divide by two to find how to find the Area of a Triangle. The area of a rectangle formula and Area of a Triangle formula are similar except that you divide by two when finding the Area of a Triangle. Usually, you will see a dashed line in a triangle that illustrates the height. Follow this process to answer what is the area of a triangle for any triangle.

4 Quick Steps to Complete Area of a Triangle Examples

Determine the length of the base.
Determine the height of the triangle.
Multiply the base times the height and then divide by two.
Be sure that your answer uses correct units.

Try the Practice Quiz on How to Find the Area of a Right Triangle

Watch the video explanation of our Area of a Triangle Worksheet

Watch our free video on how to find Area of Triangle. This video shows how to solve problems that are on our free Area of Triangles worksheet that you can get by submitting your email above.

Watch the free Area of a Triangle video on YouTube here: Area of a Triangle Video

Video Transcript:

This video is about how to find the area of triangle. You can get the area of a triangle worksheets used in this video for free by clicking on the link in the description below. A triangle is just a three-sided figure. When thinking in terms of finding the area of a triangle you can think of it as half of the area of a rectangle that has the same side lengths as the triangle. Area of a rectangle is equal to the length times the width, or you could also think of it as the base times the height. Area of a triangle is also equal to the base times the height except you have to divide by two. It’s kind of the same formula as a rectangle except the area of a triangle is half the size of a similar rectangle. Typically, the formula used is area of a triangle is base times the height divided by two or sometimes it’s shown as one-half base times height. It does not matter which formula you use, you will get the same answer for the area of a triangle.

In the case of this example triangle here, we have a height of 8 feet and a base of 12 feet. We know our area formula is area of a triangle is base times the height divided by two. In the case of this example we know the height is going to be eight feet and we know the base is going to be 12 feet because it’s the base of the triangle. When we substitute into our area formula, we’re going to use 12 feet for the base, that’s going to go where the base was, times eight feet for the height, eight goes where the height was and then we still divide by two. Then we are going to simplify the formula 12 times 8 first and you get 96 divided by 2 and 96 divided by 2 is 48 and our units are feet. It’s 48 feet squared. Let’s do a couple practice problems on our area of a triangle worksheet.

Jumping down to the first problem on our area of a triangle worksheet we have a triangle that has a base of 12 inches and a height of 5 inches. We already know that the formula for area of a triangle is base times the height and then divided by 2. We know our base is 12 inches because it’s the base of the triangle and we know the height is 5 inches. We are going to use our formula for a triangle and we’re going to substitute in 12 for the base. We’re going to say 12 for the base times the height which, in this case, is 5. We’re going to use 5 for the height and then divided by 2 which is in the formula 12 times 5 is 60. When we simplify, we’ll get 60 divided by 2 and then 60 divided by 2 simplifies to 30. And then our units are inches so it’s 30 inches squared.

The last problem we’re going to do on our area of a triangle worksheet is number five. This is a good example problem for finding area of a triangle because the height is on the interior of this triangle. The area formula for a triangle is base times the height and then divide by two. The base in this case is going to be 18 inches. It runs the entire length of the triangle so that’s our base and the height will be 7 inches because it’s the distance from the base to the vertex of the triangle. Now we substitute our base and our height into our formula. Base is 18 inches so that goes in for b times the height which is 7 inches so that goes in for h and then divided by 2. Then when we simplify 18 times 7 we will get 126 divided by 2 and then 126 divided by 2 is 63 and our units are inches. The answer is 63 inches squared. Try these practice problems and more on the area of triangle worksheet above.