Sails on sail boats take advantage of which type of energy?

Determine the maximum r-value of the polar equation r =3+3 cos 0

Can anybody me with this? ? (picture included.)

The experiment done in lab is repeated, using a ball that has unknown mass m. you plot your data in the form of f 2 versus m/l, with f in rev/s, m in kg, and l in m. your data falls close to a straight line that has slope 3.19 m/(kg · s2). use g = 9.80 m/s2 and calculate the mass m of the ball.