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Nonagon - GCSE Maths Definition

Reviewed by: Dan Finlay

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A nonagon is a polygon (2D shape with straight sides) with nine sides, and nine angles. In a regular nonagon, all nine sides will be of equal length, and all nine angles will be equal. The exterior angle of a regular nonagon can be found by dividing 360° by 9, so is 40°. Therefore, the interior angle of a regular nonagon is 180° - 40° = 140°, and the interior angle sum is 140° x 9 = 1260°. In GCSE Mathematics, a nonagon may feature in geometric problems, where finding unknown side lengths, angles, perimeters and/or areas is required.

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Dan Finlay

Reviewer: Dan Finlay

Expertise: Maths Subject Lead

Dan graduated from the University of Oxford with a First class degree in mathematics. As well as teaching maths for over 8 years, Dan has marked a range of exams for Edexcel, tutored students and taught A Level Accounting. Dan has a keen interest in statistics and probability and their real-life applications.

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