Since, it is a regular pyramid with square base having side 9 in.
The perimter of base is,
[tex]P=4\times s.[/tex][tex]P=4\times9[/tex][tex]P=36\text{ in.}[/tex]
The base area is,
[tex]A=s^2[/tex][tex]A=9^2[/tex][tex]A=81in^2[/tex]
The slant height is given as,
[tex]l=\text{ 8 in.}[/tex]
Therefore the lateral area is,
[tex]L=\frac{1}{2}\times P\times l[/tex][tex]L=\frac{1}{2}\times36\times8[/tex][tex]L=144in^2\text{.}[/tex]
The surface area of regular pyramid is, the sum of lateral area and base area.
[tex]S=L+A[/tex][tex]S=\text{ 144}+81[/tex][tex]S=225in^2[/tex]
Hence the lateral area of regular pyramid is
