Question

the area of a semi circular field is 1925 km. find the cost of fencing around the field at a rate of rupees 5.25 per metre. (Answer = Rs 945)​

Answer 1

Answer:

Length of the fence

Total cost / Rate

= R s .5280 R s .24 / m e t r e Rs.5280Rs.24/metre = 220 m

So, length of fence = Circumference of the field

∴ 220m = 2πr = 2 x 22 7 227 x r

So, r = 220 × 7 2 × 22 220×72×22 m = 35

Answer 2

Answer:

Given :.

Area of semi circular field = 1925km

we know that

Area of semi circle = 1/2 πr^2

(simply yar half of the area of circle)

Now

Area of semi circle = 1925

1/2 ×22/7 ×r^2 = 1925

r^2 = 1925×2×7/22

r^2 = 1925×7/11 (by simplification)

r^2 = 1225

r = √1225

r = 35km

Now we know that

Fencing is done on perimeter

so

perimeter of circle

= πr +2r

= 22/7 ×35 + 2×35

= 110+70

=180km

Now cost of 1km fencing = 5.25rupee

Cost of 180km fencing =

180×5.25

= 945rupee

Answer = 945rupee

A