# Example 5

- Author:
- Walch Education

- Topic:
- Quadrilaterals, Square

A square is a quadrilateral with two pairs of parallel opposite sides, consecutive sides that are perpendicular, and all sides congruent, meaning they have the same length.
Quadrilateral

*ABCD*has vertices*A*(–1, 2),*B*(1, 5),*C*(4, 3), and*D*(2, 0). Determine if this quadrilateral is a square.*Note*: Drag the blue points to try different figures.- Plot the quadrilateral on a coordinate plane.
- First show the figure has two pairs of parallel opposite sides. Calculate the slope of each side using the general slope formula.
- Observe the slopes of each side.
- Show that the quadrilateral has four congruent sides.
- Make connections.