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

The side of a square exceeds the side of another square by $4\, cm$ and the sum of the areas of the two squares is $400\, cm^2$. The dimensions of the squares are?

In a quadrilateral $ABCD$,the sides $AB, BC, CD, DA$ measure $20\, m, 13\, m, 17\, m$ and $10\, m$ respectively,and the diagonal $AC$ is $21\, m$. The area of the quadrilateral is ........ $m^2$.

$ABC$ is a triangle. $AB = 5 \text{ cm}$,$AC = \sqrt{41} \text{ cm}$,and $BC = 8 \text{ cm}$. $AD$ is perpendicular to $BC$. What is the area (in $\text{cm}^2$) of triangle $ABD$?

How many bricks,each measuring $25\, cm \times 15\, cm \times 8\, cm$,will be required to build a wall $10\, m \times 4\, dm \times 5\, m$ if $\frac{1}{10}$ of its volume is occupied by mortar?

Two sides of a plot measure $32 \ m$ and $24 \ m$ and the angle between them is a perfect right angle. The other two sides measure $25 \ m$ each. The area of the plot in $m^{2}$ is: