Jharne De and Ranjana Kumar Solutions for Chapter: Area of Polygons, Exercise 1: Mental Maths

The value of $10 \mathrm{hectares}$ is equal to _____ ${\mathrm{m}}^2$.

If side $\mathrm{a}$ if a square is halved, then the area will be _____ . 

If two squares of side $\mathrm{x} \mathrm{cm}$ are placed side by side, then the area of the resultant polygon will be _____ .

If the length of a rectangle is doubled and its breadth is halved, then its area will be _____ .

The area of the right-angled triangle whose base is $\mathrm{a}$ and altitude is $\mathrm{b}$ will be _____ .

The area of an equilateral triangle of side $4 \mathrm{cm}$ is $4\sqrt{k} {\mathrm{cm}}^2$. The value of $k$ is  _____ .

If you join the midpoints of the sides of a square whose area is $36 {\mathrm{cm}}^2$, the area of the new square formed will be _____ .

If the perimeters of two squares are $20 \mathrm{cm}$ and $24 \mathrm{cm}$ then the difference of their areas will be _____ .