A rectangle has a length of $(2\mathrm{.}9+-0\mathrm{.}2)m$ and a width of $(1\mathrm{.}1+-0\mathrm{.}2)m.$ Calculate the area and the perimeter of the rectangle, and give the uncertainty in each value.

$($a$)$ Calculate the area and give its uncertainty. $($Enter your answers in $m^2.)$

$m^2+-,m^2$

$($b$)$ Calculate the perimeter of the rectangle and give its uncertainty. $($Enter your answers in m$.)$

$m+-$

m