12 videos
2 skills
Not all things with four sides have to be squares or rectangles! We will now broaden our understanding of quadrilaterals!

Quadrilateral overview

VIDEO 8:24 minutes
"Quad" means "four" and "lateral" means "line." A quadrilateral is literally a shape with four sides (lines) and four angles. Let's learn the difference between concave and convex quadrilaterals as well as trapezoids, parallelograms, and ...

Quadrilateral properties

VIDEO 5:07 minutes
How about this: we are given a 4-sided shape and asked to determine whether its properties qualify it to be called a quadrilateral (or category of quadrilaterals). Check it out.

Quadrilaterals: kites as a geometric shape

VIDEO 5:38 minutes
Is a kite a quadrilateral? Is it a rhombus? A parallelogram? Let's find out.

Quadrilaterals: find the type exercise

VIDEO 2:49 minutes
Take a look at the given data and determine what type of quadrilateral we have.

Quadrilateral types

Identify quadrilaterals based on pictures or attributes.  Quadrilaterals included are parallelograms, rhombuses, rectangles, and squares.

Proof: Opposite sides of parallelogram congruent

VIDEO 8:30 minutes
Proving that a figure is a parallelogram if and only if opposite sides are congruent

Proof: Diagonals of a parallelogram bisect each other

VIDEO 9:06 minutes
Proving that a quadrilateral is a parallelogram if and only if its diagonals bisect each other

Proof: Opposite angles of parallelogram congruent

VIDEO 4:08 minutes
Showing that opposite angles of a parallelogram are congruent

Quadrilateral angles


Proof: Rhombus diagonals are perpendicular bisectors

VIDEO 4:04 minutes
Proving that the diagonals of a rhombus are perpendicular

Proof: Rhombus area half product of diagonal length

VIDEO 5:07 minutes
Showing that we can find the area of a rhombus by taking half the product of the lengths of the diagonals

Area of a parallelogram

VIDEO 5:42 minutes
Guess what's interesting about the opposite sides of a parallelogram? That's right....they are parallel! Let's find the area--base times height

Whether a special quadrilateral can exist

VIDEO 5:08 minutes
Proving whether a special quadrilateral can exist

Rhombus diagonals

VIDEO 4:38 minutes
Proof that the diagonals of a rhombus are perpendicular bisectors of each other