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:
| 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