In a parallelogram $ABCD$,the base $AB$ and the corresponding altitude $DM$ are $16 \, cm$ and $12 \, cm$,then the area of $ABCD =$ ................ $cm^{2}$.

According to Heron's formula,the area of a triangle $=$ ...........

$A$ field in the form of a parallelogram has sides $60 \, m$ and $40 \, m$ and one of its diagonals is $80 \, m$ long. Find the area of the parallelogram.

Write True or False and justify your answer.
The cost of levelling the ground in the form of a triangle having the sides $51 \, m$,$37 \, m$,and $20 \, m$ at the rate of $Rs \, 3$ per $m^2$ is $Rs \, 918$.

$A$ triangle and a parallelogram have the same area. If the sides of the triangle are $10 \, cm$,$17 \, cm$,and $21 \, cm$,and the parallelogram stands on the base $12 \, cm$,find the height of the parallelogram. (in $, cm$)

The sides of a triangle are $a \, cm$,$b \, cm$,and $c \, cm$. Also,its semi-perimeter is $s \, cm$. If $s - a = 10 \, cm$,$s - b = 15 \, cm$,and $s - c = 12 \, cm$,then $s = \dots \, cm$.