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:

How to Find the Area of a Triangle

Question

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

Step-by-Step:

1

Start with the formula:

Area = ½(b1 + b2)h

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.

Answer:

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

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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

See Also

What is a triangle? Find the area of a triangle using trigonometry What is trigonometry? What is an angle? What are the types of triangles? Equilateral triangles Isosceles triangles Scalene triangles Find the area of a triangle ( interactive widget)