Looking for a certain math symbol

Question

I have a very simple question. I'm wondering how to type a certain symbol in TeX. I've never encountered this symbol before today, and even after perusing the list of TeX symbols I can't find it. I saw a problem like this:

Add

$6<200^\circ-4<50^\circ$

Except instead of <200 the 200 was sort of... in the <. Like the < was to the left and below the 200. Imagine $\sqrt{200}$ but instead of a square root to the left and above, you have a < but to the left and below.

By the way, I tried Detexify.

Answer 1

You are describing the so called Steinmetz notation for complex numbers (or angle notation): the number on the left is the magnitude, the one on the right is the argument of the complex number. You can use the \phase command from the steinmetz package.

\documentclass{article}
\usepackage{steinmetz}

\begin{document}
$6\phase{200^\circ}-4\phase{50^\circ}$
\end{document}

Answer 2

This is just an extension of Luigi's answer where the siunitx package is used to typeset the physical quantities in a consistent way:

\documentclass{article}

\usepackage{steinmetz}
\usepackage{siunitx}

\begin{document}

$6\phase{\ang{200}} - 4\phase{\ang{50}}$

\end{document}