Area of a Triangle (CIE IGCSE Maths: Extended)

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Maths

Area of a Triangle

How do I find the area of a non-right triangle?

The area of any triangle can be found using the formula

$A = \frac{1}{2} a b \sin C$

- Where C is the angle between sides a and b

Be careful to label your triangle correctly so that C is always the angle between the two sides
Sin 90° = 1 so if C = 90° this becomes Area = ½ × base × height

Exam Tip

Remember to check that your calculator is in degrees mode!
The formula for the area of a triangle can be found in the list of formulas on page 2

Worked example

The following diagram shows triangle $ABC$ . $AB = 32 cm$ , $AC = 1.1 m$ , $B \hat{A} C = 74 °$ . 3-3-2-area-rule-we-question

Calculate the area of triangle .

3-3-2-ai-sl-area-rule-we-solution

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Author: Amber

Amber gained a first class degree in Mathematics & Meteorology from the University of Reading before training to become a teacher. She is passionate about teaching, having spent 8 years teaching GCSE and A Level Mathematics both in the UK and internationally. Amber loves creating bright and informative resources to help students reach their potential.