Consider a flat plate at an angle of attack in a viscous

Consider a flat plate at an angle of attack in a viscous supersonic flow; i.e., there is both skin friction drag and wave drag on the plate. Use linear theory for the lift and wave-drag coefficients. Denote the total skin friction drag coefficient by C, and assume that it does not change with angle of attack. 

(a) Derive the expression for the angle of attack at which maximum lift-to-drag ratio occurs as a function of C and freestream Mach number. 

(b) Derive the expression for the maximum lift-to-drag ratio as a function of C f and freestream Mach number M.