In Geometry, a pentagon is a two-dimensional number having 5 sides and 5 angles. In a pentagon, an edge is developed when the 2 sides the the pentagon re-publishing a typical point. Since the number of vertices in a pentagon is five, the number of angles in a pentagon is five. In this article, we are going to discuss the angles in a pentagon, together as internal angles, exterior angles, the sum of angle in a pentagon, etc., in detail with plenty of examples.

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Before mentioning the angles in a pentagon, permit us very first discuss what a pentagon is? and also different types of pentagons.

Pentagon and its Types

A pentagon is a close up door two-dimensional polygon with 5 sides and 5 angles. Based on the properties, a pentagon can be share into various types. Castle are:

Regular Pentagon: A pentagon having actually all that is sides and interior angles are equal.

Irregular Pentagon: every the political parties of a pentagon space not equal and also the interior angles are not of the very same measurement.

Convex Pentagon: every the internal angles are much less than 180° and also all the vertices suggest outwards. A continual pentagon is a convex pentagon.

Concave Pentagon: If one of the internal angles that a pentagon is greater than 180° and also if among the vertices points inward, then it is called a concave polygon.

The following number depicts the meaning of a continuous pentagon, irregular pentagon, and also concave pentagon respectively.


Sum of angles in a Pentagon

The sum of angles in a pentagon is the sum of 5 angles of the pentagon. Currently let us discuss the amount of interior and also exterior angle of a pentagon.

Sum of internal Angles in a Pentagon

Pentagon is developed from three triangles, so the sum of angles in a pentagon = 3 × 180° = 540°.

We can also calculate the amount of internal angles of the pentagon in the complying with way:

We recognize that the amount of the internal angles that a polygon of n sides = (n – 2) × 180°.

Since a pentagon has actually 5 sides, the amount of interior angles of a pentagon is = (5-2)× 180° = 3× 180°= 540°.

Hence, the amount of interior angles the a pentagon is 540°.

Sum that Exterior angle in a Pentagon

We know that the formula to calculation the sum of inner angles that a polygon is (n – 2) × 180°.

Hence, each interior angle = <(n – 2) × 180°>/n.

We know that each exterior angle is supplementary to the inner angle.

Thus, native the above formula, we deserve to derive each exterior edge = <180°n -180°n + 360°>/n = 360°/n

Therefore, the amount of exterior angle of a polygon = n(360°/n).

As, the number of sides in a pentagon is 5, n=5.

Thus, the sum of exterior angles of a pentagon = 5(360°/5) = 360°.

Interior angle of a regular Pentagon

The angles formed by two adjacent pairs of sides are referred to as interior angles of a pentagon.

Number of sides = number of vertices = variety of interior angles = 5

Two inner angles the share a typical side are called nearby angles or adjacent interior angles.


A constant pentagon has all its 5 sides equal and all five angles are also equal. Hence, the measure up of each inner angle that a constant pentagon is given by the below formula.

Measure the each interior angle = <(n – 2) × 180°>/n = 540°/5 = 108°.

Here, n = variety of sides


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Exterior angle of a consistent Pentagon

Exterior angle of a pentagon space the angle formed exterior the pentagon v its sides when the sides of the pentagon space extended. Each exterior edge of a pentagon is equal to 72°.

Since the sum of exterior angles of a continual pentagon is same to 360°, the formula to calculate each exterior edge of a continual pentagon is offered as follows:

The measure up of each exterior edge of a pentagon = 360°/n = 360°/5 = 72°.


Central edge of a Pentagon

The measure up of the main angle the a continual pentagon makes a circle, i.e. Total measure is 360°. If we division pentagon into 5 congruent triangles, climate the edge at one vertex of them will certainly be 72° (360°/5 = 72°).


Angles in a Pentagon Examples

Example 1:

Three angles of a pentagon room 80°, 70° and also 100°, climate the other two angles deserve to be 145° and 145° or 120° and also 180°?


Given 3 angles are 80°, 70° and also 100°.

Sum of three angles = 80° + 70° + 100° = 250°

We understand that the sum of all the 5 angles that a pentagon is 540°.

Sum the the other two angles = 540° – 250° = 290°


145° + 145° = 290°

120° + 180° = 300°

Hence, the other two angles of a pentagon space 145° and 145°.

Example 2:

Find the value of x from the below-given number of the pentagon.



Given that, among the angles of a pentagon is a appropriate angle, i.e. 90°.

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By angle sum residential or commercial property of a pentagon,

x + 90° + 115° + 125° + 106° = 540°

x + 436° = 540°

x = 540° – 436°

x = 104°

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