Phase shift circuit, with R=20 k, C=0.01 uF, R1=43 k. Determine the phase shift at: a) 500Hz b) 1 kHz c) 2 kHz The answer for this question are a) -2...

Phase shift circuit, with R=20 k, C=0.01 uF, R1=43 k. 

Determine the phase shift at: a) 500Hz b) 1 kHz c) 2 kHz 

The answer for this question are

a) -2 tan^-2 (2pi*20k*0.01*10^-6*500) = -64.28 degree.

b) -2 tan^-2 (2pi*20k*0.01*10^-6*1000)= -102.98 degree.

c) -2 tan^-2 (2pi*20k*0.01*10^-6*1000)= -136.61 degree

So my question is, if we need to interchange R and C, and repeat the calculations. How can we do that and get the answer for them to be a=115.72, b=77.02, c=43.39 all of them in degree