New posts in Quadrilateral

Olympiad level | Similar Triangles

Why are parallelograms defined as quadrilaterals? What term would encompass polygons with greater than two parallel pairs?

Maximize area of a quadrilateral given three sides

Side length of a quadrilateral incribed on a circle

Find the angle in a quadrilateral

Where does this property involving quadrilaterals come from?

Given a trapezoid with base $AD$ larger than side $CD$. The bisector of $\angle D$ meets $AB$ at $K$. Prove $AK > KB$

A conjecture involving prime numbers and parallelograms

If a quadrilateral has a pair of equal opposite sides, and a pair of equal opposite angles, then is it necessarily a parallelogram?

Is there a formula to calculate the area of a trapezoid knowing the length of all its sides?