1
Andrea has 3 tiles.
One is a regular octagon, one is a regular pentagon
and one is a regular hexagon.
Andrea thinks the 3 tiles will fit together perfectly,
as shown in the diagram.
Show calculations to prove that she is wrong.

Right so to find the interior angles of a shape you need to find the number of sides in a shape and minus 2
You then times this number by 180 to get the sum of interior angles for that shape
Let’s start with the octagon
It has 8 sides so you need to do 6*180 which gives you 1080
You divide this by 8 which gives you 135
This is one angle in the octagon
If you do this for all of the shapes you get 135, 108 and 120 degrees
If you add these all up you get 363 which is 3 degrees off of 360 which would be a perfect fit