Similar - GCSE Maths Definition
Reviewed by: Dan Finlay
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In GCSE Mathematics, similar shapes are enlargements of each other. The shapes are the same (triangles, pentagons, etc) and have the same size interior angles, but one has longer/shorter side lengths than the other.
Similar shapes will have their corresponding sides in the same ratio. For example, for two similar triangles, if one side length is 8 cm and the other is 16 cm (a ratio of 1:2), the same ratio will apply to the other sides - if a second side of the smaller triangle is 3 cm, the corresponding side on the similar triangle will be 6 cm.
Knowing, or deducing, that two shapes are similar allows us to solve geometric problems involving side length and area. The concept of similarity can also be extended to two and three dimensions.
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