diff --git a/src/1_complex_numbers.md b/src/1_complex_numbers.md
index 0a6be97023135a8a25d6709363d57ccdde7be604..e023bbfe568a4b74d1b6b2081378fb8f31d49d3e 100644
--- a/src/1_complex_numbers.md
+++ b/src/1_complex_numbers.md
@@ -122,10 +122,10 @@ $$\varphi = \begin{cases} \arctan(b/a) &{\rm for ~} a>0; \\
It turns out that using this magnitude $|z|$ and phase $\varphi$, we can write any complex number as
$$z = |z| e^{{\rm i} \varphi}$$
When increasing $\varphi$ with $2 \pi$, we make a full circle and reach the same point on the complex plane. In other words, when adding $2 \pi$ to our argument, we get the same complex number!
-As a result, the argument $\varphi$ is defined up to $2 \pi$, and we are free to make any choice we like:
+As a result, the argument $\varphi$ is defined up to $2 \pi$, and we are free to make any choice we like, such as
$$\begin{align}
--\pi < \varphi < \pi {\rm (left image)} \\
--\frac{\pi}{2} < \varphi < \frac{3 \pi}{2} {\rm (right image)} \end{align} $$
+-\pi < \varphi < \pi \textrm{ (left)} \\
+-\frac{\pi}{2} < \varphi < \frac{3 \pi}{2} \textrm{ (right)} \end{align} $$
