Maths · Circle, conic sections: A standard form of equations of a circle, the general form of the equation of a circle, its radius and centre

If the radius of the circle is increased by then the area is increased by

If the radius of the circle is increased by \( 100 \% \) then the area is increased by

  • A. \( 100 \% \)
  • B. 200\%
  • C. 300\%
  • D. 400\%

Step-by-step solution

Let original radius be r. Original area = πr^2. Increase radius by 100% -> new radius = r + r = 2r. New area = π(2r)^2 = 4πr^2. Increase in area = 4πr^2 - πr^2 = 3πr^2. Percentage increase = (3πr^2 / πr^2) × 100% = 300%.
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