Area of rhombus

Q.

The floor of a building consists of $3000$ tiles which are rhombus-shaped and each of its diagonals are $45cm$ and $30cm$ in length. Find the total cost of polishing the floor, if the cost per $m^2$ is $Rs.4.$

Q.

Find the area of a rhombus whose side is$5cm$ and whose altitude is $4.8cm$. If one of the diagonals is $8cm$ long, find the length of the other diagonal.