(a)
Lateral surface area of prism =720cm²(Given) Perimeter x height = 720
36 x height = 720
[tex] ∴ Height\: of\: prism = \frac{720}{36} = 20\\(b) Total \:surface\: area\: of\: prism = 2 x \:base\: area\: + L.\: S.\: A\: of \:prism \\ = \frac{2 \times \sqrt{3} }{4} \times( {12}^{2} ) + 720 \\ = (72 \sqrt{3} + 720) {cm}^{2} \\ = (72 \times 1.732 + 720) {cm}^{2} \\ = 844.704 \frac{}{} {cm}^{2} [/tex]
