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## Basic geometry and measurement

# Classifying quadrilaterals

CCSS.Math:

There are many different relationships between the types of quadrilaterals. Parallelograms have two sets of parallel sides, rhombuses are parallelograms with equal side lengths, and squares are rhombuses with right angles. Though there is overlap, not all quadrilaterals fit into each category. Created by Sal Khan.

## Want to join the conversation?

- If quad means four, what means five?(25 votes)
- Pent means five like the pentagon it has five sides.(11 votes)

- So let me get this straight, Rhombi are squares because they both have sides of equal length, Quadrilaterals are not rhombi because a quadrilateral can be many different shapes and it is not a parallelogram for the same reason, a parallelogram can be other things. Right? Do I have that correct? Please Answer, thanks.(9 votes)
- Rhombi are not all squares, but squares are all rhombi, just like all rhombi are quadrilaterals but not all quadrilaterals are rhombi. A square is just a more specific type of rhombus, just like a rhombus is a more specific type of square. It's just like fish are all animals (unless they're toys) but not all animals are fish.(10 votes)

- At0:34-0:39, did he also mean to say that all sides are of equal length? A rectangle is also a quadrilateral with only 90-degree angles, but all the sides aren't always the same length.

UPDATE (Mar. 8, 2021): Since a rhombus has sides of equal length, Sal already implied that when bringing up the square. I fully understand now!(13 votes)- Yes, rhombus is a quadrilateral with 4 sides of equal length. So rectangles are not always rhombus.(5 votes)

- 2:15a square is always a rhombus(10 votes)
- Of course it really is. A square has the same identities of a rhombus.(5 votes)

- how can a parallelogram and quadrilateral not always be a rhombus? Can someone explain.(6 votes)
- In word problems, be careful not to assume that a quadrilateral has parallel sides or equal sides unless that is stated. A parallelogram has two parallel pairs of opposite sides. A rectangle has two pairs of opposite sides parallel, and four right angles. ... No, because a rhombus does not have to have 4 right angles.(9 votes)

- How do I make my character grow(4 votes)
- get more points you can get 850 for every vid you watch(1 vote)

- Is impossible to tarigle is has4side(4 votes)
- Yes it is impossible since triangle means 3 sided shape and so it is only used to name 3 sided shapes.

Hope this helps!😀(3 votes)

- Hey so i did the practice and it said classify the shape and the shape is square but its rotate to diamond position and i clicked on rectangle because they said squares are rectangles.Rectangles are quadarilaterals with 4 right angles and opposite sides are equal. The shape is a quadrilateral but it does not have 4 right angles so it is not a rectangle.BUT THEN THEY SAID Yes a square is also a rectangle because all 4 angles are right angles and the opposite sides are equal. I DONT GET IT WHY MY ANSWER IS WRONG SOMEONE PLZ EXPLAIN(5 votes)
- If it’s rotate it to a diamond position count it as a diamond and not a square(1 vote)

- how long has the name ''square'' been around?(3 votes)
- That's a really good question. but, unfortunately, I don't know.(4 votes)

- giggidy giggidy giggidy(4 votes)

## Video transcript

A parallelogram is a blank with
two sets of parallel lines. So let's see what
the options are. So one option is
a quadrilateral. And a parallelogram is
definitely a quadrilateral. A quadrilateral is
a four-sided figure, and it is definitely
a four-sided figure. A parallelogram is
not always a rhombus. A rhombus is a special case of a
parallelogram where not only do you have to sets
of parallel lines as your sides, two
sets of parallel sides, but all of the sides are the
same length in a rhombus. And a square is a special
case of a rhombus where all of the angles
are 90 degrees. So here, all we can say
is that a parallelogram is a quadrilateral. And so let's check our answer. And it's always a good
idea to look at hints. And so it'll kind of say the
same thing that we just said, but it would say it for
the particular problem that you're actually looking at. Let's do a few more of these. Suzanne is on an expedition
to save the universe. Sounds like a reasonable
expedition to go on. For her final challenge,
she has to play a game called Find
the Rhombuses. A wizard tells her that she
has a square, a quadrilateral, and a parallelogram,
and she must identify which of the
shapes are also rhombuses. Which of these shapes should
she pick to save the universe? So a square is a special
case of a rhombus. Just to remind ourselves, a
rhombus, the opposite sides are parallel to each other. You have two sets
of parallel sides. A square has two sets
of parallel sides, and it has the extra condition
that all of the angles are right angles. So a square is definitely
going to be a rhombus. Now, all rhombuses
have four sides. So all rhombuses
are quadrilaterals. But not all quadrilaterals
are rhombuses. You could have a quadrilateral
where none of the sides are parallel to each other. So we won't click this one. Once again, a parallelogram. So all rhombuses
are parallelograms. They have two sets
of parallel sides, two sets of parallel
line segments representing their sides. But all parallelograms
are not rhombuses. So I would say that if
someone gives you square, you can say, look, a square is
always going to be a rhombus. A quadrilateral isn't always
going to be a rhombus, nor is a parallelogram
always going to be a rhombus. We got it right.