Area

The term ‘area’ is a quantity giving the size of a two-dimensional region or shape within a given enclosed border.

The formulae for the area $ A $ of common shapes are:

shape formula note
square $ A = a^2 $ where $ a $ is the length of one of the sides
rectangle $ A = ab $ where $ a $ is the base and $ b $ is the height
circle $ A $ = $ \pi r^2  $ where $ r $ is the radius
triangle $ A = 0.5ab $ where $ a $ is the base and $ b $ is the height

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