Polygons

Sides and Angles of Polygons

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Copy this in your math journal.
How do you know what the interior angles measure of each of the polygons?


Count the number of angles (a triangle has three angles)

Subtract 2 (3-2 = 1)


multiply by 180 degrees (1 x 180)

That gives you the measure of the interior angles for the polygon.

Try this with the rest of your shapes


The formula is 

n - 2 times 180

n-2 * 180
Triangle = 180 degrees
Quadrilateral = 360 degrees
Pentagon = 540 degrees
Hexagon = 720 degrees
Heptagon = 900 degrees
Octagon = 1,080 degrees
Nonagon = 1,260 degrees
Decagon = 1,440 degrees

Triangle

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A 3-sided polygon (a flat shape with straight sides).
A triangle has three sides and three angles.
The three angles always add to 180°

Quadrilateral

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Any four-sided shape is a Quadrilateral.





  • Four vertices (or corners).
  • The interior angles add up to 360 degrees.
  • Quadrilateral just means "four sides"
    (quad means four, lateral means side).