Basic Calculations and Formula for Regular Polygons

Central Angles

Central Angle = 360 ÷ number of sides

Number of Sides Central Angle
Triangle 3 120
Square 4 90
Pentagon 5 72
Hexagon 6 60

Interior Angles

For a plane: Interior Angle = 180 - (360 ÷ number of sides)

For a sphere: Interior Angle > 180 - (360 ÷ number of sides)

Number of Sides Interior Angle
Triangle 3 60
Square 4 90
Pentagon 5 108
Hexagon 6 120

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