In Unit 15, we learned that a quadrilateral has four-sides. It is two-dimensional (a fl at shape), closed (the lines join up), and has straight sides.
A polygon is a two-dimensional shape with three or more sides.
A parallelogram is a quadrilateral for which both pairs of opposite sides are parallel (and therefore, opposite angles equal). A rhombus is a quadrilateral with four equal sides. It is sometimes called a diamond.
You can identify what kind of quadrilateral you have using the following fl ow chart. Quadrilaterals
The four angles in a quadrilateral sum to 360°
By the end of this section you should understand: ● what a rhombus and parallelogram are
● that opposite angles in a parallelogram are equal to each other
Non-parallelograms
Opposite sides not equal
Opposite angles not equal
Parallelograms
Opposite sides are equal
Opposite angles are equal
Rhombus
All four sides are equal Opposite angles are equal