The sides of a rectangular field are 198 m and 175 m long. Its area is equal…

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The sides of a rectangular field are 198 m and 175 m long. Its area is equal to the area of a circular field.

What is the perimeter (in m) of the circular field? Take π = 22/7.

Take π = 22/7

Answer: B. 660ConceptWhen two plane figures have equal areas, equate their area formulas. For a rectangle, A = l × b; for a circle, A = πr2, and the circle’s perimeter…

  1. A.

    658

  2. B.

    660

  3. C.

    667

  4. D.

    654

Attempted by 19 students.

Show answer & explanation

Correct answer: B

Concept

When two plane figures have equal areas, equate their area formulas. For a rectangle, A = l × b; for a circle, A = πr2, and the circle’s perimeter (circumference) is C = 2πr.

The shared area determines r first; the circumference is then obtained from that radius.

Application

  1. Calculate the rectangle’s area: A = 198 × 175 = 34,650 m2.

  2. Equate the areas: πr2 = 34,650. With π = 22/7, r2 = 34,650 × 7/22 = 11,025.

  3. Take the positive square root because radius is a length: r = √11,025 = 105 m.

  4. Calculate the circumference: C = 2 × 22/7 × 105 = 660 m.

Cross-check

For r = 105 m, the circle’s area is (22/7) × 1052 = 34,650 m2, exactly equal to 198 × 175. Therefore, the required perimeter is 660 m.

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