This is a 'standard' difficulty, and some elementary math texts get this tangled up.
The way mathematicians work, think, and use these words, we are 'inclusive'. So something with four Equal sides DOES have two pairs of opposite sides equal. That means is also a rectangle.
Look at it in reverse.
If you give some definition of a rectangle: eg. four right angles, then you can start to look at figures which have this property.
When you happen to find an example with four equal angles, you will agree it is a rectangle, even before you check whether the sides are ALSO equal. If the sides are also equal, it is still a rectangle and is also a square. The 'image' of this is a collection of all rectangles as a big circle, and the collection of all squares as a smaller circle INCLUDED inside the bigger one.
Take numbers. We can have all even numbers. We can have all numbers divisible by 10. The second collection is 'included' in the set of even numbers. They did not stop being even, they just picked up an extra additional property.
Does that help?
Pamela Paramour wrote:
> Is a square a rectangle? When did the geniuses of the Math world come > up with that one? If you refer to Webster, a square is a > parallelogram with 4 EQUAL sides and 4 right angles. Wouldn't that > rule out a rectangle? Sorry, but I'm no math wiz, just wondering why > my daughter got that answer wrong on a math quiz. Would love this > explained in Laymons Terms. :)