As shown in figure below, water $($specific weight $=9800\frac{N}{m^3})$ is in contact with a square panel; $d=2\mathrm{.}3m,h=2m.$

$($a$)$ Calculate the depth to centroid.

$($b$)$ Calculate the resultant force on the panel.

$($c$)$ Calculate the distance from the centroid to the centre of pressure $($CP$).$