Question

Explain how square is a quadrilateral

Answer 1

A square is a quadrilateral because it has four sides.
It is a regular quadrilateral because all four sides and angles are equal.

Explanation:
A quadrilateral is any figure with four sides.
Let's take for example a rectangle (because we have to prove it with squares), it has four sides, so it's a quadrilateral.
And as well as a square has four sides, kites, parallelograms, rhombuses, etc. are also quadrilaterals.

Answer 2

Hey mate here is your answer,

In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or (100-gradianangles or right angles).It can also be defined as a rectangle in which two adjacent sides have equal length. A square with vertices ABCD would be denoted as ABCD.