Interior angle – The interior angle of a pentagon is 108 degree. If we want to find the interior angle of a pentagon then we use formula:

Interior angle = (180n – 360)/n,

Where, the value of ‘n’ is 5; because pentagon has five sides.

Exterior angle – The exterior angle of a pentagon is 72 degree. In this a linear pair is formed with the interior angle. The formula for finding the exterior angles of a pentagon is:

Exterior angle = (180 – interior angle),

Area – the area of a pentagon is approximately 1.72 s

^{2},

Where‘s’ is the length of a side, if we want to find the area of a pentagon when length of a side is given then we use following formula:

Area =

__s__

^{2}N,4tan (180/N)

Where’s’ denotes the length of any side.

‘N’ is the number of sides.

Tan is used to find the Tangent function.

If the radius is given then the formula for finding the area of a pentagon is:

Area =

__R__

^{2}Nsin (360/N),2

Where, ‘r’ is the radius,

‘N’ is the number of sides,

Sin is the trigonometric function which is calculated in degrees.

If in radius or apothem is given then the formula for finding the area of pentagon is:

Area = A

^{2}N tan (180/N),

Where, A is the length of the apothem or in radius of a pentagon.

There are some types of pentagon which are:

Regular or irregular– The pentagon which has all the sides and angles are equal known as regular pentagon and the angles and side are not equal is known as irregular known as irregular pentagon.