Question: Let $\displaystyle T$ is a normal operator on a finite-dimensional inner product space $\displaystyle V$. Show that $\displaystyle N(T)=N(T^*)$ and that $\displaystyle R(T)=R(T^*)$.

I think that I got the first part. Suppose $\displaystyle x \in N(T)$ Then $\displaystyle T(x)=0$. But $\displaystyle ||T(x)|| = ||T^*(x)||$ for all $\displaystyle x$ so $\displaystyle T^*(x)=0$ as well. So $\displaystyle x \in N(T^*)$, which means that $\displaystyle N(T) \subseteq N(T^*)$. The same logic goes the other way around and we conclude $\displaystyle N(T) = N(T^*)$.

But what about $\displaystyle R(T)=R(T^*)$? I know that $\displaystyle R(T^*) = N(T)^{perp}$ but how does that help?