A3 Which of the following values is not taken by the function $f(x)=\cos x$?
(A) $\frac{3 \sqrt{3}}{2}$
(B) $\frac{2 \sqrt{3}}{5}$
(C) $-\frac{\sqrt{6}}{4}$
(D) $\frac{\sqrt{2}+\sqrt{3}}{4}$
(E) $-\frac{\sqrt{3}}{2}$
A3. The range of values for the given function is $[-1,1]$. Let's check the values at the provided solutions and determine that the value at A exceeds the value of 1.