What is the inner radius of the circular opening of the pot so formed ?

Consider the following for the next two (02) items that follow :<br>A pot is made from a hollow sphere of inner radius 20 cm by cutting its upper portion horizontally. The height of the pot is 30 cm.

  1. A. 10\sqrt{2} cm
  2. B. 15 cm
  3. C. 10\sqrt{3} cm
  4. D. 12 cm

Correct Answer: C. 10\sqrt{3} cm

Explanation

The sphere's radius is R=20. Since the pot's height is 30 cm, the plane cuts the sphere 10 cm above the center (30-20=10). Using Pythagoras' theorem on the cross-section: r^2 + 10^2 = 20^2 \implies r = \sqrt{400-100} = \sqrt{300} = 10\sqrt{3} cm.

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