Quadrilaterals

Quadrilateral overview

"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 rhombi.

Quadrilateral properties

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

Is a kite a quadrilateral? Is it a rhombus? A parallelogram? Let's find out.

Quadrilaterals: find the type exercise

Take a look at the given data and determine what type of quadrilateral we have.

Proof: Opposite sides of parallelogram congruent

Proving that a figure is a parallelogram if and only if opposite sides are congruent

Proof: Diagonals of a parallelogram bisect each other

Proving that a quadrilateral is a parallelogram if and only if its diagonals bisect each other

Proof: Opposite angles of parallelogram congruent

Showing that opposite angles of a parallelogram are congruent

Proof: Rhombus diagonals are perpendicular bisectors

Proving that the diagonals of a rhombus are perpendicular

Proof: Rhombus area half product of diagonal length

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

Guess what's interesting about the opposite sides of a parallelogram? That's right....there are parallel! Let's find the area--base times height

Whether a special quadrilateral can exist

Proving whether a special quadrilateral can exist

Rhombus diagonals

Proof that the diagonals of a rhombus are perpendicular bisectors of each other