Three sides of a triangular field are $20\, m$,$21\, m$,and $29\, m$ long,respectively. The area of the field is.......$m^2$.

The dimensions of a field are $20 \text{ m}$ by $9 \text{ m}$. $A$ pit $10 \text{ m}$ long,$4.5 \text{ m}$ wide and $3 \text{ m}$ deep is dug in one corner of the field and the earth removed has been evenly spread over the remaining area of the field. What will be the rise in the height of the field as a result of this operation? (in $m$)

The areas of a square and a rectangle are equal. The length of the rectangle is greater than the side of the square by $5 \text{ cm}$ and the breadth is less than the side of the square by $3 \text{ cm}$. Find the perimeter of the rectangle (in $\text{cm}$).

The diameters of two concentric circles are $8\, cm$ and $10\, cm$. The area of the region between them is

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

If the diagonal of a square is doubled to make another square,the area of the new square will