Our friends the square, is a four sided shape with no variation, that is all of the internal angles measure to 90° and all of the sides of the same length.



So as you can see, from the diagram the sides are denoted as “A” and they are all the same length.


Unlike the triangle, especially in this particular case the equilateral triangle, the internal angles do not add up to 180° but in fact add up to 360°.


This will remain the case for the rest of the N sided polygon that we look at, in fact when we move onto the five sided shape at the Pentagon, we will find that the internal angles add up to 540° and in the case of the hexagon 720°


You will note that I’m showing the internal angles, but there is also an external angle to consider, and strangely enough the sum of the external angles is always 360° irrespective of the number of sides that the shape possesses.  We will come to this later.