Assume these hexagons are similar. which changes will result in a pair of non-similar hexagons?
в
с
dh
el
o
doubling each side length in abcdef
subtracting 1 from each side length in ghijkl
o
adding 15 degrees to angles g, h, and i, and subtracting 15 degrees from angles ). k and
reducing each side length in ghijkl by one-third of the original length
adding 3 to each side length in ghijkl

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.

pi or 3.14159265359 is an irratinal decimal