$$\left. \begin{array} { l } { \quad P = 100 b a r = 1000 N / c m ^ { 2 } } \\ { \quad A = 7.85 c m ^ { 2 } } \end{array} \right.$$
$r\in \mathrm{R}$
$P=100abr$
$b\in \mathrm{R}$
$a\in \mathrm{R}$
