A circle has a circumference of 31.4 cm. What is its radius? (2021)

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Question: A circle has a circumference of 31.4 cm. What is its radius? (2021)

Options:

Correct Answer: 5 cm

Exam Year: 2021

Solution:

Circumference = 2πr. Thus, r = Circumference/(2π) = 31.4/(2π) = 5 cm.

A circle has a circumference of 31.4 cm. What is its radius? (2021)

A circle has a circumference of 31.4 cm. What is its radius? (2021)

Step 1: Understand that the circumference of a circle is given by the formula: Circumference = 2πr, where r is the radius.
Step 2: We know the circumference is 31.4 cm. So we can set up the equation: 31.4 = 2πr.
Step 3: To find the radius (r), we need to rearrange the equation. We can do this by dividing both sides by 2π: r = 31.4 / (2π).
Step 4: Now, calculate the value of 2π. Using π ≈ 3.14, we find 2π ≈ 6.28.
Step 5: Substitute 6.28 into the equation: r = 31.4 / 6.28.
Step 6: Now, perform the division: r ≈ 5 cm.

Circumference of a Circle – The relationship between the circumference and radius of a circle is given by the formula C = 2πr.
Solving for Radius – To find the radius, rearranging the circumference formula is necessary: r = C/(2π).