What is the relationship between any two circles?

Two circles will touch if the distance between their centres, , is equal to the sum of their radii, or the difference between their radii. Two circles will intersect at two points when. The centre of one circle will lie on the other circle when or . Two circles are concentric when

18

step-by-step explanation:

draw the shape and you will see that f and k are actually at adjacent vertices (points of the hexagon that are neighboring).   so find the distance between (1,2) and (4,2).   that is easy since (1,2) and (4,2) is just a vertical distance to count, which is 3.   it is a regular polygon which means all sides are congruent.   you have 6 sides (hexa) so multiply 6 by 3 to receive 18.