Just to close I will now talk briefly about DEGREES and RADIANS. We have been working in degrees in this document but in other branches of maths, particularly calculus the preferred unit of measurement for angles is the radian.


If we consider the length of an ‘arc’ of a circle, ie: that section of the circumference marked in bold in the diagram opposite.

There will come a point where the angle between the two drawn radii is such that the length of the arc is equal to the length of the radius. 


When this point is reached, the angle between the radii is equal to 1 radian, or 1rad or 1c being approximately 57.2960