# How to Find the Area of a Triangle (Mathematics Lesson)

# How to Find 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:

# A Real Example of How to Find the Area of a Triangle

#### An Example Question

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

Start with the formula:
Area = ½bh

**Don't forget:**½bh = ½ × b × h

Step 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 cm

^{2}**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 cm

^{2}.

# Another Real Example of How to Find the Area of a Triangle

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

##### Curriculum

##### Interactive Test

**show**

Here's a second test on finding the area of a triangle.

Here's a third test on finding the area of a triangle.

##### Note

# What Is a Triangle?

A triangle is a flat shape with three straight sides and three corners (also called vertices).There are different types of triangle:

# What's in a Name?

A triangle has three corners and so three angles.Just as a tricycle has three wheels, and a tripod has three legs, a shape with three angles in called a triangle.

# Areas of Triangles and Rectangles

The area of a triangle is ½bh.The area of a rectangle is bh.

The area of the triangle is half that of the rectangle with the same base length and height.

Can you see from the image of a right-angled triangle below that this is the case?

What about this triangle below?