The area of the grass that will be watered is given by 800/9 pi ft^2.
What is the area of a circle?
The area of a circle of radius r is given by:
A = πr²
In this problem, a rotating sprinkler head sprays water as far as 20 feet, hence the radius is of r = 20 ft.
It covers a central angle of 80º, while an entire circle has 360º, hence the area of grass that will be watered corresponds to 80/360 = 2/9 of the area of the circle.
Hence the watered area in ft² is given by-
A = 2/9 π × (20)²
= 800π/ 9
Therefore, the area of the grass that will be watered is given by 800/9 pi ft^2.
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