There are six types of quadrilaterals and these quadrilaterals can be classified by the relationships of their sides and angles.
• Parallelogram
• Rectangle
• Square
• Rhombus
• Trapezoid
• Kite

## How to identify a parallelogram

A parallelogram is a four-sided polygon with two pairs of parallel and equal sides. The following figure is a parallelogram.

In a parallelogram, all the followings are true:

• Opposite sides are parallel (AB || DC and AD || BC)
• Opposite sides are equal (AB = DC and AD = BC )
• Opposite angles are equal (angle A = angle C and angle B = angle D)

## How to identify a rectangle

A rectangle is a parallelogram with 4 right angles. The following figure is a rectangle.

In a rectangle, all the followings are true:

• Opposite sides are parallel (HG || EF and HE || GF)
• Opposite sides are equal (HG = EF and HE = GF)
• All four angles are equal to 90 degrees ( angle E = angle F =  angle G = angle H = 90 degrees)

## How to identify a square

A square is a rectangle with 4 equal sides.The following figure is square.

In a square, all the followings are true:

• Opposite sides are parallel (JK || IL and JI || KL)
• All four sides are equal (JI = KL = JK = IL)
• All four angles are equal to 90 degrees ( angle I = angle J =  angle K = angle L = 90 degrees)
Rhombus: A rhombus is a parallelogram with 4 equal sides. The following figure is a rhombus.

In a rhombus, all the followings are true:

• Opposite sides are parallel (PO || MN and PM || ON )
• All four sides are equal (PO = ON = NM = MP )
• Opposites angles are equal ( angle M = angle O and angle N = angle P)

## How to identify a trapezoid

Trapezoid: A trapezoid is a quadrilateral with only one pair of parallel sides. There are three types of trapezoids.

Scalene trapezoid: A scalene trapezoid is a trapezoid with no equal sides.The following is a scalene trapezoid.

Right-angled trapezoid: A right-angled trapezoid is a trapezoid with two right angles. The following is a right-angle trapezoid.

Isosceles trapezoid: In an isosceles trapezoid, non-parallel sides are equal. The following is an isosceles trapezoid.

## How to identify a kite

A kite is a quadrilateral with two pairs of adjacent sides that are equal. Furthermore, no opposite sides are equal.

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