The diagonals of a rhombus are $40 \, cm$ and $42 \, cm$. Find its area in $cm^2$.

The perimeter of a triangular field is $420\, m$ and its sides are in the ratio $6: 7: 8$. Find the area of the triangular field (in $m^2$).

How much paper of each shade is needed to make a kite as shown in the figure,where $ABCD$ is a square with diagonal $44 \, cm$? (in $cm^2$)

In quadrilateral $ABCD$,$AB = 40 \, cm$,$BC = 35 \, cm$,$CD = 48 \, cm$,$DA = 29 \, cm$ and $BD = 29 \, cm$. Find the area of quadrilateral $ABCD$. (in $, cm^2$)

In Heron's formula,$s$ represents ............

If $a, b, c$ are the lengths of three sides of a triangle,then the semiperimeter $(s)$ of the triangle is ..........