To calculate the lateral area of the prism you must start finding the perimeter of the base of the prism to do that we must analyse the triangles base
by definition the lateral area of a triangular prism is the area of the sides of the prism without the base and top faces
the perimeter will be
[tex]\begin{gathered} 8+8+5 \\ 21 \end{gathered}[/tex]
the height of the prism will be 9
the lateral area will be
[tex]\begin{gathered} (21)\cdot9 \\ 189 \end{gathered}[/tex]
