Given the lengths of the right triangle:
[tex]\begin{gathered} 12a^4^{} \\ \text{and } \\ 16a^4 \end{gathered}[/tex]To find the perimeter, use the formula:
[tex]P=a+b+\sqrt[]{a^2+b^2}[/tex]Thus, we have:
[tex]P=12a^4+16a^4+\sqrt[]{(12a^4)^2+(16a^4)^2}[/tex][tex]\begin{gathered} P=28a^4+\sqrt[]{144a^4+256a^4} \\ P=28a^4+\sqrt[]{400a^4} \\ P=28a^4+20a^4 \\ P=48a^4 \end{gathered}[/tex]Therefore, the expression is:
[tex]48a^4[/tex]