If the diameter of each circle is $14 \, cm$ and $DC = CE$,find the area of $\Delta BDE$ in $cm^2$.

If '$x$' is the median (altitude) of an equilateral triangle,then its area is?

$A$ tank $4 \, m$ long, $2.5 \, m$ wide, and $6 \, m$ deep is dug in a field $10 \, m$ long and $9 \, m$ wide. If the earth dugout is evenly spread over the field, the rise in level of the field will be (in $cm$):

Mid-points of a triangle containing sides $12 \, cm$,$18 \, cm$,and $26 \, cm$ are joined to each other. Find the area of the triangle formed by joining the mid-points.

The circumference of two circles is $88 \text{ m}$ and $220 \text{ m}$ respectively. What is the difference between the area of the larger circle and that of the smaller circle (in $m^2$)?

Seven equal cubes each of side $5 \, cm$ are joined end to end. Find the surface area of the resulting cuboid? (in $cm^2$)