A circle has an area of 154 cm². What is the radius? (2019)

Practice Questions

Q1
A circle has an area of 154 cm². What is the radius? (2019)
  1. 7 cm
  2. 14 cm
  3. 21 cm
  4. 28 cm

Questions & Step-by-Step Solutions

A circle has an area of 154 cm². What is the radius? (2019)
  • Step 1: Write down the formula for the area of a circle, which is Area = πr².
  • Step 2: We know the area is 154 cm², so we can set up the equation: 154 = πr².
  • Step 3: To find r², we need to isolate it. Divide both sides by π: r² = 154/π.
  • Step 4: Use the approximate value of π, which is 3.14. So, r² = 154/3.14.
  • Step 5: Calculate 154 divided by 3.14, which is approximately 49.04.
  • Step 6: Now, to find r, take the square root of 49.04: r = √49.04.
  • Step 7: The square root of 49.04 is approximately 7 cm.
  • Area of a Circle – The area of a circle is calculated using the formula A = πr², where A is the area and r is the radius.
  • Square Root Calculation – Finding the radius involves taking the square root of the area divided by π.
  • Approximation of π – Using an approximate value for π (3.14) can lead to slight inaccuracies in the final answer.
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