Question

A pond 100 metres in diameter is surrounded by a circular grass walk 2 metres wide how many square metres of grass is there on the walk​

Answer 1

Answer:

The area of the grass walk is 640.885 sq. meters.

Step-by-step explanation:

The pond is circular in shape with diameter 100 meters.

And the grass walk surrounding the pond is 2 meters wide.

Consider the image below.

The radius of the pond is:

$r=\frac{diameter\ of\ pond}{2}\\ =\frac{100}{2}\\ =50$

Radius of the total circular area is:

$R=\frac{diameter\ of\ pond +4 }{2}\\ =\frac{100+4}{2}\\ =52$

Area of grass walk = Area of bigger circle - Area of pond

                               $=\pi R^{2}-\pi r^{2}\\=\pi (R^{2}-r^{2})\\=\pi (52^{2}-50^{2})\\=204\pi \\=640.885$

Thus, the area of grass walk is 640.885 sq. meters.

Answer 2

The area of the grass walk is 640.885 sq. meters.

Step-by-step explanation:

The pond is circular in shape with diameter 100 meters.

And the grass walk surrounding the pond is 2 meters wide.

Consider the image below.

The radius of the pond is:

$r=2diameter of pond=2100=50</p><p></p><p></p><p>$

Radius of the total circular area is:

$R=2diameter of pond+4=2100+4=52</p><p></p><p></p><p>$

Area of grass walk = Area of bigger circle - Area of pond

$\begin{gathered}=\pi R^{2}-\pi r^{2}\\=\pi (R^{2}-r^{2})\\=\pi (52^{2}-50^{2})\\=204\pi \\=640.885\end{gathered}=πR2−πr2=π(R2−r2)=π(522−502)=204π=640.885</p><p>$

Thus, the area of grass walk is 640.885 sq. meters.