Quadrilateral how many sides

Depending on people's definition, this may or may not be a trapezoid. If you say it's exactly one pair of parallel sides, this is not a trapezoid, because it has two pairs. If you say at least one pair of parallel sides, then this is a trapezoid. So I'll put that in a little question mark there. But there is a name for this, regardless of your definition of what a trapezoid is. If you have a quadrilateral with two pairs of parallel sides, you are then dealing with a parallelogram. So the one thing that you definitely can call this is a parallelogram.

And I'll just draw it a little bit bigger. So it's a quadrilateral, and if I have a quadrilateral, and if I have two pairs of parallel sides. So the opposite sides are parallel. So that side is parallel to that side, and then this side is parallel to that side there-- you're dealing with a parallelogram. And then parallelograms can be subdivided even further. If the four angles in a parallelogram are all right angles, you're dealing with a rectangle. So let me draw one like that.

This is all in the parallelogram universe, what I'm drawing right over here. This is all the parallelogram universe. So it's a parallelogram, which tells me that opposite sides are parallel. And then if we know that all four angles are 90 degrees. And we've proven in previous videos how to figure out the sum of the interior angles of any polygon. And using that same method you could say that the sum of the interior angles of any quadrilateral is actually degrees. And you see that in this special case as well.

But maybe we'll prove it in a separate video. But this right over here we would call a rectangle. Parallelogram-- opposite sides parallel and we have four right angles. Now, if we have a parallelogram where we don't necessarily have four right angles, but where we do have the length of the sides being equal, then we're dealing with a rhombus.

So let me draw it like that. So it's a parallelogram. This is a parallelogram, so that side is parallel to that side, this side is parallel to that side. And we also know that all four sides have equal length. So this side's length is equal to that side's length, which is equal to that side's length, which is equal to that side's length.

Then we are dealing with a rhombus. So one way to view it-- all rhombi are parallelograms. All rectangles are parallelograms.

All parallelograms you cannot assume to be rectangles. All parallelograms you cannot assume to be rhombi. Now, something can be both a rectangle and a rhombus. Here we list the special names. See the articles on each type for their definitions and special properties. Compare quadri- to Spanish cuatro. Just as triangles and quadrilaterals are special types of polygons, there are many subclasses of quadrilaterals. Like all polygons that have more than three sides, quadrilaterals can be convex like these , , , or concave like these ,.

Quadrilaterals can be classified by whether or not their sides, angles, diagonals, or vertices have special properties. The classification schemes taught in elementary school involve the number of pairs of parallel sides, and the congruence of sides, and whether or not all the angles are right angles all angles are congruent.

The names of many of these special quadrilaterals are also typically part of the elementary curriculum, though little else about the properties of these figures may be studied until high school.

Elementary school typically has children learn the names of. The square is also the name of the regular quadrilateral — one in which all sides are congruent and all angles are congruent. Though the names that are given to individual figures does not change, the way that they are grouped may depend on the characteristics used to sort them.

In the classification scheme below, rectangles F and B have the right hand column to themselves, but parallelograms are not grouped in a way that excludes A , which is not a parallelogram. Children in primary grades often find it hard to assign anything geometrical or otherwise simultaneously to two categories. Similarly, students tend to treat rectangles and parallelograms as disjoint classes, rather than seeing a rectangle as a special type of parallelograms.

Another possible way to classify quadrilaterals is by examining their diagonals. This may be accessible for middle grade students who have learned about perpendicular lines and bisectors. A Quadrilateral has four-sides , it is 2-dimensional a flat shape , closed the lines join up , and has straight sides.

Also see this on Interactive Quadrilaterals. Try drawing a quadrilateral, and measure the angles. Some types are also included in the definition of other types! For example a square , rhombus and rectangle are also parallelograms. See below for more details. Also opposite sides are parallel and of equal length. A rhombus is a four-sided shape where all sides have equal length marked "s".