GeoGebra Classroom

# Sum of Interior Angles

Look at the triangle above. You can move the points anywhere you please, but make sure the shape stays as a triangle and the angles are inside the triangle. When you add up the angles, what do you get?

Now look at the shape above. You can move the points around, just make sure the shape stays a quadrilateral and the angles stay inside. When you add up all the angles, what do you get?

Looking at the shape, how many triangles do you think would fit in the quadrilateral?

Looking at this polygon, how many triangles do you think would fit here if the shape were cut?

Adding up all the angles, what is the total amount of degrees?

If there are three triangles and each one is 180 degrees, how many degrees is in the three triangles?

Let's look at this final polygon. How many triangles do you think can fit in this hexagon?

Looking at all the angles, what is the angle measurement of this shape?

What is the total angle measurement of 4 triangles added up?

Surely, you have started to see a pattern now. Now, look at the following expressions. Which one do you think is the correct one to obtain the total number of angles from a polygon with "n" amount of sides?

Select all that apply
• A
• B
• C
• D
Check my answer (3)
Challenge Question

Find the angle measurement of this polygon with the previous equation.