A pentagon has actually 5 sides, and can it is in made native three triangles, so you know what ...

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... Its internal angles add up to 3 × 180° = 540°

And once it is regular (all angles the same), climate each edge is 540° / 5 = 108°

(Exercise: make certain each triangle here adds approximately 180°, and check the the pentagon"s interior angles add up come 540°)

The interior Angles that a Pentagon add up to 540°

## The basic Rule

Each time we include a side (triangle come quadrilateral, square to pentagon, etc), we add one more 180° come the total:

ShapeSidesSum ofInterior AnglesShapeEach Angle
 If the is a Regular Polygon (all sides space equal, every angles space equal) Triangle 3 180° 60° Quadrilateral 4 360° 90° Pentagon 5 540° 108° Hexagon 6 720° 120° Heptagon (or Septagon) 7 900° 128.57...° Octagon 8 1080° 135° Nonagon 9 1260° 140° ... ... .. ...See more: Difference Between Role Strain And Role Conflict, Researchgate ... Any Polygon n (n−2) × 180° (n−2) × 180° / n

So the general dominion is:

Sum of internal Angles = (n−2) × 180°

Each angle (of a consistent Polygon) = (n−2) × 180° / n

Perhaps an example will help:

### Example: What about a constant Decagon (10 sides) ? Sum of inner Angles = (n−2) × 180°
= (10−2) × 180°
= 8 × 180°
= 1440°

And because that a constant Decagon:

Each internal angle = 1440°/10 = 144°

Note: interior Angles are sometimes dubbed "Internal Angles"

interior Angles Exterior Angles degrees (Angle) 2D forms Triangles quadrilaterals Geometry Index