13. For a rectangular wing the following two pairs of measurements are known; {CI = 1.0; Cm, 1/2 = +0.17} and {c = 0.2; Cm,1/2 = -0.05} (where Cm,1/2 is the moment coefficient about the mid-chord point). a) Calculate the variation of the centre of pressure for values of the lift coefficient of C = 0.0, 0.1, 0.2, 0.4, 1.6, 0. b) Plot the variation of the centre of pressure as a function of the lift coefficient.