Table of Contents

## What is Diagonal?

A diagonal is a line segment that connects two opposite corners of a polygon or polyhedron.

## Key Definitions to Remember While learning Diagonals

A diagonal line is a line that is not horizontal or vertical. It is a line that goes from one corner of a square to another corner.

A diagonal is a line that goes from one corner of a square to another corner.

A square has four diagonals.

## Number of Diagonals in a Polygon

A polygon is a closed figure formed by a finite number of straight line segments that are joined end to end. A polygon has at least 3 sides and at most 5 sides. A polygon has at least 3 diagonals and at most 8 diagonals.

## Diagonal of a Polygon Formula

The diagonal of a polygon is a line segment that connects any two opposite vertices. The length of the diagonal is the length of the hypotenuse of a right triangle whose other two sides are the length of the polygon’s sides.

## Diagonal of a Square

The diagonal of a square is the length of the hypotenuse of a right triangle with the base of the triangle being the length of one side of the square and the height of the triangle being the length of the other side of the square.

## Properties of the Diagonals in a Square

The diagonals in a square are both the same length and they are perpendicular to each other.

## Diagonal of a Rectangle

The diagonal of a rectangle is the line segment that connects the opposite corners. The length of the diagonal is the length of a side of the rectangle multiplied by the square root of 2.

## Diagonal of a Rhombus

The diagonal of a rhombus is the line segment that connects two opposite vertices of the rhombus.

## Diagonal of a Parallelogram

The diagonal of a parallelogram is the line segment that connects two opposite corners of the parallelogram.

## Diagonal of Parallelogram

The diagonal of a parallelogram is a line segment that connects two opposite vertices.

## d12 + d22 = 2(a2+b2)

d12 + d22 = 4a2