Sagot :
Answer:
Originally Answered: Which one is easier to measure radius or the diameter of a circle? If you are given the centre, it is the radius which is easier to measure. If not, and you only have a ruler, then by sliding it as a secant over the circle, you can read off the diameter as the length of the longest chord of it.
[tex]\huge\color{purple}{\boxed{\tt{Answer:}}}[/tex]
A circle is the set of all points, on a 2D-plane, at distance r from the centre. That's a concise and elegant definition; try doing so using the diameter (distance d). Then, having defined circles using the radius, it becomes convenient to also define the radian measure of angles in terms of the radius of a circle.