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 perimeter of a non-square rhombus is $20 \, cm$. One of its diagonals is $8 \, cm$. The area of the rhombus is.........$cm^2$

What will be the cost of gardening a $1 \text{ m}$ broad boundary around a rectangular plot having a perimeter of $340 \text{ m}$ at the rate of $₹ 10$ per square metre?

What is the area of a given right-angled triangle?
$I.$ The length of the hypotenuse is $5\, cm$.
$II.$ The perimeter of the triangle is four times that of its base.
$III.$ One of the angles of the triangle is $60^{\circ}$.

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 ........ $m^2$.

The perimeter of an isosceles triangle is $14 \ cm$. The lateral side and the base are in the ratio $5:4$. The area of the triangle in $cm^2$ is: