# How to Find the Area of a Triangle: Lesson for Kids

Instructor: Trisha Fyfe

Trisha has taught college and K-12 English, reading, writing, and math. She has a master's degree in teaching.

Look around you; measurements are everywhere! We measure the length and height of things all the time. The area of a shape is another important measurement to understand. In this lesson, we will explore the steps to finding the area of triangles.

## What's on the Inside?

Sometimes we need to determine the measurement of the space inside the borders of a shape, not just the distance around the shape. The distance around the edges of a shape is the perimeter. The measurement, or size, of a surface on a shape is called the area. The area includes any space that is inside the borders of this surface. You can find the area of any shape: squares, rectangles, circles, triangles, and even some really funny looking shapes. To find the area of a shape, we need to know which formula to use. Formulas are used all the time in math, and they are really important to know. The formula for finding the area of a triangle is A = ½ bh. This means that we multiply ½ times the base of the triangle (b) times the height of the triangle (h) to get the area of the triangle (A). ## A Triangular Sail: What's the Area?

Let's give it a try. Practice makes perfect, right? Say you are measuring out how much fabric will be needed to make a triangular sail for a sailboat. The base for the triangle is 6 feet and the height is 3 feet. Can you figure out how much square feet of fabric will be needed?

While the formula starts with ½ , this doesn't mean we have to start with this number. In multiplication we can multiply the numbers in any order and still get the same answer. So, first let's multiply 6 x 3 = 18. Next, we multiply this number (18) by ½.

Here's the thing though, multiplying any number by ½ just means you are dividing this number by 2. This is helpful to know if you haven't practiced multiplying by fractions quite yet! We divide our first number (18) by 2 (18 ÷ 2 = 9). We need 9 square feet of fabric for this sail.

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