(ii) The pressure coefficient at a particular point on the surface of a wing is given by the equation C = 2 yM 1 + (y - 1)M/0 z () 1 1 +(y - 1)M 2 1+ 8 where M is the local Mach number and M is the free stream Mach number. Assuming isentropic flow, calculate the critical pressure coefficient when the critical Mach number is 0.89.