true
A cent (penny) is circular so the "greatest distance" is simply its diameter. Since 1858, all US cents have had a diameter of 19.05 mm.
SD max
The radius is half of the diameter. The diameter is double the radius. If you don't have either one then it can be pretty complicated to get an accurate measurement. If you know where the center of the circle is, then you can draw any line through the center, and measure the distance between the two points where the line hits the curved part of the circle. But if all you have is the circle, with no point to show you where the center is, then there's no simple method for measuring it precisely. You can bisect two chords, and the bisecting lines will intersect at the center, or you can just measure the greatest width (although this is not so accurate.) See the related link, The Parts of the Circle, below this answer.
-7
The greatest magnitude possible is just short of 50%. That occurs when a number just smaller than 15 is rounded down to 10.
true
No Narrowest victory was 1 point (1991) Largest victory was by 45 points (1990)
... equator.
The diameter is the width of the widest part, where the circumference is greatest.
The greatest distance across a circle is its diameter.
measuring tape
perihelion
1.25
Elliptical Galaxies
A cent (penny) is circular so the "greatest distance" is simply its diameter. Since 1858, all US cents have had a diameter of 19.05 mm.
An eighth of an inch.
In the US, I believe the 50 cent piece has the greatest diameter.