Unit 9 Section 5 : The Area of a Triangle

This section introduces the formula for the area of a triangle, which can be seen below.

The height is called the perpendicular height because it is at a right-angle to the base.
Below is an example of the formula being used to find the area of a triangle.

Example Question

Below are two triangles, each with their base and perpendicular height indicated.

Practice Questions
Work out the answer to each of these questions then click on the button marked

to see whether you are correct.

What is the area of triangle A?

What is the area of triangle B?

Exercises

Work out the answers to the questions below and fill in the boxes. Click on the

button to find out whether you have answered correctly. If you are right then

will appear and you should move on to the next question. If

appears then your answer is wrong. Click on

to clear your original answer and have another go. If you can't work out the right answer then click on

to see the answer.

Question 1
Find the area of each of these triangles.

Part 1
(a) cm²

(b) m²

(c) cm²

(d) mm²

(e) cm²

(f) cm²

(g) cm²

(h) mm²

Question 2
Find the areas of the shapes below.
In each case, you will need to divide the shape into one rectangle and one triangle, then add the areas together.
Dashed lines have been included on each shape to help you with this.

(a) cm²

(b) cm²

(c) cm²

(d) cm²

You have now completed Unit 9 Section 5

Your overall score for this section is

Correct Answers
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Incorrect Answers
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There were questions with wrong answers.
There were questions you didn't attempt.

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Produced by A.J.Reynolds January 2001