First draw a straight line. Then take the compass and make a circle. Next using a different measurement, (you decide, a random one is fine) use the 2 intersections of the circle and line to create two marks that meet. This point should line up with your original point. Now just connect the 2.
the answer is this seems to be a trick question because you have to divide 6 meters by two to get 3 cm and the four also gets divided by 2 cm and that is how i got the aanswer d