Are you asking for the letter or what the line is called because if it's just the letter then it is r if it is the name then its a plane intersect.
You would cross multiply.
14 over 31.5
and X over 10.5
10.5 times 14 is 147
divide that by 31.5 which is 4 1/3
and that is how fast she can run
4 1/3 mph
Circle = perpendicular cross section of a cylinder
cone = perpendicular cross section of a pyramid
