For this problem you may assume the fact that $K_1(C_0(D)) = 0$. Let $n > 1$, let $\omega = e^{\frac{2πi}{n}}$, and let $E_n$ be the space obtained from $D$ by identifying $z$ and $\omega z$ for all $z \in \partial D$. Thus $C(E_n) = \{f \in C(D) : f(z) = f(\omega z)$ if $|z| = 1\}$. Compute the K-theory of $C(E_n)$ and give explicit representatives for the generators.
I'm confused on how to start. I believe that $E_n$ is homeomorphic to a sphere, but I am not sure how to compute K-theories of topological spaces.