$Ac=1A_c^2[(-0\mathrm{.}3{)}^2+(0\mathrm{.}05{)}^2+(0\mathrm{.}2{)}^2+(0\mathrm{.}05{)}^2\}$

$b.$

$\frac{1}{2}{A}_c^2[(-0\mathrm{.}3{)}^2+(0\mathrm{.}05{)}^2+(0\mathrm{.}2{)}^2+(0\mathrm{.}05{)}^2]$

$c.$ none $of$ them

$d.$

$e.$ zero