this may help you
he functión Cot[x/2] is not continuos in the points
x=2nπ, where n=0,1,2,3,...
You can check it with a calculator. So the function is not continuos in
the domain the problem gives you, so the Rolle's theorem can not be
applied. If the inteverval was,
[π/2,3π/2]
Then we could apply the Rolle's theorem.
