Challenge Level

In the GeoGebra interactivity below there is

Can you work out the angles in your triangles?

You should have found four different triangles with angles of:

40, 70, 70

80, 50, 50

120, 30, 30,

160, 10, 10

80, 50, 50

120, 30, 30,

160, 10, 10

Create some more triangles by joining three dots on the edge of the nine point circle.

Can you work out the angles each time?

When the centre dot isn't inside your triangle, you might find it a little trickier to work out the angles. Click below for a diagram that might help: