If the perimeter of a semi-circular protractor is $36 \, cm$,then its diameter is ...... $cm$?

In trapezium $ABCD$,$AB || CD$ and $AB = 2 \, CD$. Its diagonals intersect at $O$. If the area of $\Delta AOB = 84 \, cm^2$,then the area of $\Delta COD$ is equal to (in $cm^2$)

$A$ typist uses a sheet measuring $20\, cm \times 30\, cm$ lengthwise. If a margin of $2\, cm$ is left on each side and a $3\, cm$ margin on top and bottom,the percent of the page used for typing is

An oblong piece of ground measures $19$ $meters$ $2.5$ $dm$ by $12$ $meters$ $5$ $dm$. From the centre of each side,a path $2$ $meters$ wide goes across to the centre of the opposite side. Find the cost of paving these paths at the rate of $Rs.$ $12.32$ per $sq$ $meter$. (in $Rs.$)

The length of a rectangular plot is $20 \ m$ more than its breadth. If the cost of fencing the plot at $₹ 26.50/m$ is $₹ 5300$,what is the length of the plot in metres?

The sides of a triangle are $6\, cm$,$11\, cm$,and $15\, cm$. The radius of its incircle is