the solid line passes through (0,-3) and (0,9)
dotted line passes through (0,-3) and (0,-1)
see attached sketch
The diameter of the plate is 12, and the formula for finding circumference is diameter times pie. so you multiply pie (or 3.14 if you aren't using a calculator) times 12 and it should give you 37.6991. rounded to the nearest tenth, that's 37.7, hope I helped!