# How to Find the Area of a Triangle

## Finding the Area of a Triangle

The area of a triangle is found using the formula: In this formula, b is the length of the base of the triangle and h is the height of the triangle. The image below shows what we mean by the lengths of the bases and the height: ## Interactive Widget

Use this interactive widget to create a triangle and then calculate its area. Start by clicking in the shaded area.

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## How to Find the Area of a Triangle

Finding the area of a triangle is easy.

### Question

What is the area of a triangle with a base of 5 cm and a height of 3 cm, as shown below? # 1

Area = ½bh

Don't forget: ½bh = ½ × b × h

# 2

Substitute the length of the base and the height into the formula. In our example, b = 5 and h = 3.

Area = ½ × 5 × 3 = 7.5 cm2

Don't forget: ½ × a number = 0.5 × a number = a number ÷ 2.

The area of the triangle with a base of 5 cm and a height of 3 cm is 7.5 cm2.

## Slider

The slider below shows another real example of how to find the area of a triangle.

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## How to Find the Area of a Triangle Using Trigonometry

The area of a triangle can also be found using trigonometry.

The area is found using the formula: In the formula, a and b are lengths of two sides of the triangle and C is the angle between them. The image below shows what we mean by the two sides and the angle between them: Read more about how to find the area of a triangle using trigonometry