If the length of one diagonal of a rhombus is $80 \%$ of the length of the other diagonal,the area of the rhombus is how many times the square of the length of the longer diagonal?

Two sides of a triangular field are $85 \, m$ and $154 \, m$,respectively,and its perimeter is $324 \, m$. The cost of ploughing the field at the rate of ₹ $10$ per $m^2$ is (in ₹):

If the length of a rectangle is increased by $10 \%$ and its breadth is decreased by $10 \%,$ then its area

$A$ rectangular park is $65\, m$ long and $50\, m$ wide. Two cross paths,each $2\, m$ wide,are to be constructed parallel to the sides. If these paths pass through the centre of the rectangle and the cost of construction is ₹ $17.25$ per $m^2$,then find the total cost involved in the construction (in ₹).

The area of a circle is increased by $22\, cm^{2}$ when its radius is increased by $1\, cm$. The original radius of the circle is.......$cm$.

Find the perimeter (in $cm$) of a semicircle of radius $28\, cm$.