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The Area of a Triangle

To find the area of a triangle, use the following formula

Area of a Triangle Worksheet
Area of Triangle Applet
lesson
Area of a triangle Calculator
Find Height From Area
The area of a triangle is always  half the product of the height and base.

$ Area = \frac{1}{2} (base \cdot height ) $
Picture of triangle height and base

So which side is the base?

Answer: Any side of the triangle can be a base. All that matters is that the base and the height must be perpendicular.
Any side can be a base, but every base has only one height. The height is the line from the opposite vertex and perpendicular to the base. The illustration below shows how any leg of the triangle can be a base and the height always extends from the vertex of the opposite side and is perpendicular to the base. Play around with our applet to see how the area of a triangle can be computed from any base/height pairing.

The picture below shows you that the height can actually extend outside of the triangle. So technically the height does not necessarily intersect with the base.
calculator

Area of Triangle Applet

See applet on its own page
Choose Base
Formula Type
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Explanation of the Area of a Triangle

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Example 1
What is the area of the triangle picutred below?
Area
Practice Problems


Find the area of each triangle below. Round each answer to the nearest tenth of a unit.
Problem 1
What is the area of the triangle in the following picture?
Answer


Problem 2
Calculate the area of the triangle pictured below.
Answer


Problem 3
Calculate the area of the triangle pictured below.
Answer


Problem 4
Calculate the area of the triangle pictured below.
Answer


Problem 5
Calculate the area of the triangle pictured below.
Answer


Problem 6
What is the area of the following triangle?
Answer
Problem 7
What is the area of the following triangle?
Answer


Problem 8
What is the area of the following triangle?
Answer


Problem 9
What is the area of the following triangle?
Answer
Area of a Triangle Worksheet
Area of Triangle Applet
lesson
Area of a triangle Calculator
Find Height From Area