Isaac draws a regular octagon and rotate about its center which angle measures can isaac rotate the regular octagon through to map itself

A regular octagon has eight equal sides
We can draw eight isosceles triangles in a regular octagon

The angle b° is the angle we can turn the regular octagon around the map
To work out b° we can divide 360° by 8 which gives us 45°

So when we rotate the regular octagon for every 45° we can fit the octagon back to its original position