Definition

Trapezium (UK); Trapezoid (US)

A quadrilateral that has exactly one pair of parallel opposite sides is called a trapezium (trapezoid).

The two parallel sides are called bases.
The two non-parallel sides are called legs.

Parallelogram

A Parallelogram is a quadrilateral in which both pairs of opposite sides are parallel

Remember: parallelograms are not trapeziums (Why?)

Rectangle

• If each of the four angles of a parallelogram is a right angle (measures 90°), then the parallelogram is called a rectangle.
• A rectangle is a parallelogram having each of its angles 90°.

Remember: All rectangles are parallelograms (Why?)

Rhombus

A rhombus is a parallelogram all of whose sides are equal

Remember: Every rhombus is a parallelogram (Why?)

Square

A square is a rectangle all of whose sides are equal
Remember: All squares are parallelograms (Why?)
All squares are rectangles (Why?)
All squares are rhombuses (Why?)

Kite

A kite is a quadrilateral in which two pairs of adjacent sides are equal in length
AC = BC
AD = BD
Remember: A square is a kite (Why?)
A rhombus is a kite (Why?)