LO: find exterior and interior angles in regular polygons

We have to 'produce' the sides of a polygon to see the exterior angles

Notice that the interior and exterior angle will always add to give 180^o

If you walk all the way around the outside of a polygon you will have gone a full turn - hence the exterior angles of a polygon will always add to 360^o

This is useful for working out the exterior angles of a regular polygon

To work out the interior angles we can then subtract the exterior angle from 180

Interior angle of a regular pentagon = 180 - 72 = 108^o

We could then use this to find the sum of the interior angles

Sum of interior angles of a pentagon = 5 x 108 = 540^o

Thankfully this is the same answer we got in yesterday's lesson when we split the pentagon into 3 triangles and did (5-2)x180 = 3 x 180 = 540^o    :)

Further example:

Spend about 30 mins on the questions below - mark as you go (answers at bottom) - upload a photo when you're done.