The sum of all interior angles of a regular polygon is twice the sum of all its exterior angles. The number of sides of the polygon is

$A$ circular swimming pool is surrounded by a concrete wall $4 \ m$ wide. If the area of the concrete wall surrounding the pool is $11/25$ that of the pool,then the radius (in $m$) of the pool is

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

The radius and vertical height of a cone are $5 \text{ cm}$ and $12 \text{ cm}$ respectively. Then its lateral surface area is? (in $\text{cm}^2$)

In a parallelogram,the lengths of adjacent sides are $12\, cm$ and $14\, cm$,respectively. If the length of one diagonal is $16\, cm$,then find the length of the other diagonal (in $cm$).

The area of the largest circle that can be drawn inside a rectangle with sides $18 \, cm$ and $14 \, cm$ is (in $cm^2$):