1.
[tex]b = 6 \ cm\\d = 12 \ cm\\a = ?\\P = ?\\Ob = ?\\\\Z \ tw. \ Pitagorasa:\\\\a^{2}+b^{2} = d^{2}\\\\a^{2}+6^{2} = 12^{2}\\\\a^{2}+36=144\\\\a^{2} = 144-36 = 108\\\\a = \sqrt{108} = \sqrt{36\cdot3}\\\\\underline{a = 6\sqrt{3}}[/tex]
[tex]P = a\cdot b\\\\P = 6\sqrt{3}\cdot6\\\\\boxed{P = 36\sqrt{3} \ cm^{2}}\\\\Ob = 2(a+b)\\\\Ob = 2(6\sqrt{3}+6)=2\cdot6(\sqrt{3}+1)\\\\\boxed{Ob = 12(\sqrt{3}+1) \ cm}[/tex]
2.
[tex]P = \frac{a^{2}\sqrt{3}}{4}[/tex]