Four equal circles, each of radius 5cm, touch each other as showing fig.15.65. Find the area included between them.

The outer circumference of a circular race-track is 525m. The track is everywhere 14m wide. Calculate the cost of leveling the track at the rate of 50paise per square meter

A rectangular piece is 20m long and 15m wide. From its four corners, quadrants of radii 3.5m have been cut. Find the area of the remaining part.

Four cows are tethered at four corners of a square plot of side 50m, so that they just cannot reach one another. What area will be left un-grazed?

Four equal circles, each of radius a, touch each other. Show that the area between them is.