Aligning minipages in math environment! [closed]

Question

I am wondering why the mathematic lines and the text in the first minipage are not aligned the same.

I would prefer the text part (below the first math part, equation (89)) to extend to the place where the first line of the equation 89 is located.

Could you help me please?

The code:

\documentclass[a4paper,12pt, reqno]{amsbook}
\usepackage[overlay]{textpos}
\usepackage{graphicx}
\graphicspath{F:/(some path here)/pdfs/}
\usepackage{setspace}
\usepackage{caption}
\usepackage{bm}
\usepackage{cancel}

\newcommand{\e}{\mathbf{e}}
\newcommand{\parn}[1]{\left({#1}\right)}
\newcommand{\p}{\partial}
\newcommand{\strain}{\bm{\varepsilon}}
\newcommand{\brak}[1]{\left[{#1}\right]}
\newcommand{\bff}[1]{\mathbf{#1}}


\begin{document}
\frontmatter
\mainmatter
\noindent
\begin{minipage}[t]{\textwidth}
\begin{minipage}[t]{.58\textwidth}% [t] means top
 Then nabla is applied from the left
{\small\begin{align}
\nabla\times\strain\times\nabla &= \parn{\e_1\p_1 + \e_2\p_2 + \e_3\cancel{\p_3}}\times\brak{x_2\e_1\e_3+x_1\e_2\e_3}\notag\\
&=\p_1\parn{x_1}\e_3\e_3 - \p_2\parn{x_2}\e_3\e_3 = \bff{0}\quad \surd
\label{eq:}
\end{align}}
Michell-Cesaro formula; which is a path integral; is path independent for compatible strain fields therefore we take the simplest integration path\;(Fig. 6)
\end{minipage}%<- This is obligate
\hspace{0pt}
\begin{minipage}[t]{.4\textwidth}%
\vspace{0pt}%<- Fake line
\captionsetup{font=scriptsize}
\centering
\includegraphics[width=0.7\textwidth]{sol10c.pdf}%[width=0.48\textwidth]
\captionof{figure}{Inetgration path.}
\label{fig:digraph}
\end{minipage}
\end{minipage}
\end{document}