The area of a rectangular field is 1008 m². Its shorter side is 1/8 of the sum…
2023
The area of a rectangular field is 1008 m². Its shorter side is 1/8 of the sum of its longer side and one of its diagonals. What is the cost of fencing the field at ₹24 per metre?
- A.
3696
- B.
3744
- C.
3792
- D.
3840
Attempted by 10 students.
Show answer & explanation
Correct answer: C
Solution
Let the longer side of the rectangular field be l metres and the shorter side be b metres.
Given:
Area of the rectangle = 1008 m²
Shorter side is 1/8 of the sum of the longer side and a diagonal.
Therefore,
b = (l + d)/8
where d is the diagonal of the rectangle.
Rearranging,
8b = l + d
d = 8b − l
Using the Pythagorean theorem for a rectangle:
d² = l² + b²
Substituting d = 8b − l,
(8b − l)² = l² + b²
64b² − 16bl + l² = l² + b²
64b² − 16bl = b²
63b² − 16bl = 0
b(63b − 16l) = 0
Since b ≠ 0,
63b = 16l
l = (63/16)b
Using the area of the rectangle,
l × b = 1008
(63/16)b × b = 1008
63b² = 16128
b² = 256
b = 16 m
Hence,
l = (63/16) × 16 = 63 m
Perimeter of the field
= 2(l + b)
= 2(63 + 16)
= 2 × 79
= 158 m
Cost of fencing
= Perimeter × Rate
= 158 × 24
= ₹3792
Therefore, the cost of fencing the field is ₹3792.
Answer: C) 3792