The diameter of a circle is 10 cm. What is its area?
  1. 78.5 cm2
  2. 100 cm2
  3. 7.8 cm2
  4. 20 cm2
Explanation
Answer: A- If the diameter of a circle is 10 cm, its area is 78.5 cm2. Since the formula for the area of a circle is 3.14 (π) r², you can start by dividing the diameter in half in order to get the radius. In this case, 10 ÷ 2 = 5. And 5² = 25, so 3.14 x 25 = 78.5 cm2.
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