latex text in equation environment

\documentclass{article}
\begin{document}
 some text 
 \begin{equation}
c = \sqrt{a^{2} + b^{2}} text in math
\end{equation}
 more text
  \begin{equation}
c = \sqrt{a^{2} + b^{2}} \textrm{ text in math}
\end{equation}
 more text
\end{document}