Pentagon - GCSE Maths Definition

A pentagon is a polygon (2D shape with straight sides) with five sides, and five angles. In a regular pentagon, all five sides will be of equal length, and all five angles will be equal. The exterior angle of a regular pentagon can be found by dividing 360° by 5, so is 72°. Therefore, the interior angle of a regular pentagon is 180° - 72° = 108°, and the interior angle sum is 108° x 5 = 540°. In GCSE Mathematics, a pentagon may feature in geometric problems, where finding unknown side lengths, angles, perimeters and/or areas is required.