From point A to the circumference pass the AK vertices and the sharp AD to the center. Find the length of KM allowed from point K to line AD if AP = 8 and AK = 12

This is a map of the mars exploration rover opportunity predicted landing site on mars. the scale is 1cm : 9.4km. what are the approximate measures of the actual length and width of the ellipse? i mostly need to know how to set it up : )