Angles in Polygons

Use this applet to investigate the sum of angles in polygons. Is there a pattern? Can you predict the sum of the angles in a 20-sided polygon?

Use the applet...

Duane Habecker, Created with GeoGebra

 

Directions:

  1. Create a triangle of your choice. Measure each angle of the triangle and find their sum. Try one or two more triangles. Is their angle sum always the same? Record the angle sum for triangles in the table below.  and quadrilaterals in the table below.
  2. Create a quadrilateral of your choice. Measure each angle of the quadrilateral and find their sum. Try one or two more quadrilaterals. Is their angle sum always the same? Record the angle sum for quadrilaterals in the table below.
  3. Continue to fill in the table for pentagons and hexagons. Find a pattern.
  4. What is the relationship between the number of sides on the shape and the sum of the angles?
Polygon Number of sides

Sum of angles

Triangle    

Quadrilateral

   

Pentagon

   

Hexagon

   
Septagon    
Octagon    

Extension: What is the sum of the angles in a 20-sided figure?


 

 

 

 

 

Google Matched Ad