We have a problem with three different state of the ratio of flow velocity to speed of sound.
That is,
a) Mach number to evaluate is 0.2, that mean we have a subsonic state.
The equation here for lift coefficient is,

where
should be expressed in Rad.

So replacing in equation for subsonic state,

b) In this situation we have a transonic state, so we need to use the Prandtl-Glauert rule,

c) For this case we have a supersonic state, so we use that equation,
