Answer:
[tex]diagonal \: of \: square = a \sqrt{2} \\ 12 = a \sqrt{2} \\ \frac{12}{ \sqrt{2} } = a \\ \: a = 6 \sqrt{2} \\ now \: area \: of \: square = {l}^{2} \\ = (6 \sqrt{2) {}^{2} } \\ = 72cm {}^{2} \\ again \: perimeter \: of \: square = 4l \\ = 4 \times (6 \sqrt{2} ) \\ = 33.94cm[/tex]
