[tex]pp = \frac{ {a}^{2} \sqrt{3} }{4} = \frac{ {3}^{2} \sqrt{3} }{4} = \frac{9 \sqrt{3} }{4} [/tex]
[tex]h = 5cm[/tex]
[tex]pb = 3 \times 5 = 15[/tex]
[tex]pc = 2pp + 3pb \\ 2pp = 2 \times \frac{9 \sqrt{3} }{4} = \frac{9 \sqrt{3} }{2} \\ 3pb = 15 \times 3 = 45 \\ pc = ( \frac{9 \sqrt{3} }{2} + 45) {cm}^{2} [/tex]
