23. Exemplar Exercise Problesm IX

1. The area of a regular hexagon of side $a$ is the sum of the areas of the five equilateral triangles with side $a$. 

 

2. The cost of levelling the ground in the form of a triangle having the sides $51 m$, $37 m$ and $20 m$ at the rate of $Rs.3$ per $m^2$ is $Rs.918$.

 

3. In a triangle, the sides are given as $11 cm$, $12 cm$ and $13 cm$. The length of the altitude is $10.25 cm$ corresponding to the side having length $12 cm$.