Is the diameter of a circle always twice the radius?

1 Answer
Dec 25, 2015

Yes

Explanation:

Diameter AB of a circle with center O connects two points on the circle (A and B) and passes through a center (point O). Therefore, it is a sum of two segments - from a point on a circle to a center (AO) and from a center to another point on a circle (OB):
AB=AO+OB

Since a circle is a locus of all points equidistant from a center (and the distance is called the radius of a circle - r),
AO=r and OB=r.

Therefore,
AB=AO+OB=r+r=2r