Find the area of the triangle with the side lengths $51 \, cm$,$52 \, cm$,and $101 \, cm$. (in $, cm^2$)

$1$ hectare $= \ldots \ldots \text{ } m^{2}$

If the area of an equilateral triangle is $16 \sqrt{3} \, cm^{2}$,then the perimeter of the triangle is (in $cm$)

$A$ design is made on a rectangular tile of dimensions $50\, cm \times 70\, cm$ as shown in the figure. The design shows $8$ triangles,each with sides $26\, cm, 17\, cm$,and $25\, cm$. Find the total area of the design and the remaining area of the tile.

The edges of a triangular board are $6 \, cm$,$8 \, cm$,and $10 \, cm$. The cost of painting it at the rate of $9$ paise per $cm^2$ is:

$A$ triangular park $ABC$ has sides $120\,m, 80\,m$ and $50\,m$ (see Fig.). $A$ gardener Dhania has to put a fence all around it and also plant grass inside. How much area does she need to plant? Find the cost of fencing it with barbed wire at the rate of $Rs. 20$ per metre leaving a space $3\,m$ wide for a gate on one side.