Will give ! how would you use a model to determine the approximate formula for the circumference of a circle with a diameter of 6 cm, and connect the model to the actual formula?

Johnny rode his bike to a friends house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was unable to play. what was his displacement for the total bike ride trip? what could you use as a reference point ? show the steps to solve this problem.