Let radius of circular field be rm.
∴ Area of circular field is π r2m2.
∴ Cost of ploughing circular field at the rate of Rs 0.75 per
m2 = πr2x Rs 0.75 = Rs (3/4 πr2)m2
∴ 3/4 πr2 = 4158 (∵ Given cost = Rs 4158)
= r2 = 4158 x 4/3 x 7/22 ( ∵ π = 22/7)
= r2 = 63 x 4 x 7
= 9 x 7 x 4 x7
= 32 x 22 x 72
= (3x2x7)2
= 422
= r = 42 m
∴ Perimeter of circular field is P = 2 πr
= 2 x 22/7 x 42 = 264 m
∴ Cost of fencing the field = Rs 30 per meter
∴ Cost of fencing the circular field
= Rs (264 x 30)
= Rs 7920