Big Theta(Θ) symbol in LaTeX

Symbol/Unicode	Big Theta/U+0398
Type of symbol	Greek capital letter
Package (requirement)	No
Argument	No
Latex command	`\Theta`
Example	`\Theta` → Θ

Big Theta is a popular symbol in mathematics. You need to use the \Thetacommand to print this symbol in a latex document, and no package is required.

Below are some examples.

\documentclass{article}
\begin{document}
   Prove that if $ f(n)=\Theta (g(n)),\;g(n),\;$ then $g(n)=\Theta (f(n)) $\\[6pt]
   $ R(N)\;\varepsilon\;\Theta\;(f(N)) $
\end{document}