\usepackage {graphics}
\[
\begin{array}{ccccc}
 a_{11}                      \\
 a_{21} & a_{22}             \\
 a_{31} & a_{32} &
  a_{33}\Bpara{0}{7}{61}{65} \\
 a_{41} & a_{42} &
  a_{43}     & a_{44}        \\
 a_{51} & a_{52} &
  a_{53}\Bpara{-8}{-6}{-90}{58}
             & a_{54} & a_{55}
   \end{array}
\]