Grazing area: A cow is tethered with a rope and can graze 9856 sq m. Assuming a circular grazing path, find the length of the rope.

Difficulty: Easy

Correct Answer: 56m

Explanation:

Introduction / Context:This classic geometry problem links area of a circle to its radius, modeling the rope length as the radius of the grazing circle.

Given Data / Assumptions:

  • Area A = 9856 sq m
  • Grazing path is circular
  • Use π = 22/7 unless specified

Concept / Approach:Area A = πr^2 → r = sqrt(A/π). The rope length equals r.

Step-by-Step Solution:

r^2 = A / π = 9856 / (22/7) = 9856 * 7 / 229856 / 22 = 448 → r^2 = 448 * 7 = 3136r = sqrt(3136) = 56 m

Verification / Alternative check:Area with r = 56: πr^2 = (22/7)*56*56 = (22/7)*3136 = 22*448 = 9856. Perfect match.

Why Other Options Are Wrong:16m, 14m, 76m, 64m do not square to 3136 when used with π = 22/7 to produce 9856 m^2.

Common Pitfalls:Using diameter instead of radius, or incorrect π handling during division.

Final Answer:56m

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