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Regular 2-D shapes
By Anonymous on Sunday, October 24, 1999 - 01:05 pm:

I've been trying to help a friend's child with her maths and her textbook says that 2D shapes with equal sides are called 'regular' eg an equilateral triangle, a square and a honeycomb-type hexagon are all regular. One of the questions she had to answer was whether a rhombus was regular. Is it? We wondered whether the maths definition of regularity was only to do with equal sides or whether the internal angles had to be equal to, hence a rhombus would not be regular but a square is. Does anyone know?

By Alex Barnard (Agb21) on Tuesday, October 26, 1999 - 11:11 am:

Regular normally means that the sides and angles are all the same. So a rhombus is not regular but a square is. Similarly a rectangle is not regular but a square is.

AlexB.

By The Editor on Tuesday, October 31, 2000:

There is a word for a shape where the sides are all the same, but the angles are not necessarily equal: equilateral.
So a rhombus is equilateral.
Strangely, we only commonly use the word equilateral when talking about triangles, and an equilateral triangle is always regular.