Circumference of a circle with a radius of 4
Understand the Problem
The question is asking for the circumference of a circle given its radius. To find the circumference, we will use the formula C = 2πr, where r is the radius.
Answer
$C \approx 31.42$ units
Answer for screen readers
The circumference of the circle is $C \approx 31.42$ units.
Steps to Solve
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Identify the radius First, we need to clearly know the value of the radius, denoted as $r$.
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Use the formula for circumference The formula to find the circumference $C$ of a circle is given by: $$ C = 2\pi r $$ This means we will multiply $2$, $\pi$, and the radius $r$ together.
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Plug in the value of the radius For example, if the radius is $5$ units, we replace $r$ in the formula: $$ C = 2 \pi (5) $$
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Calculate the circumference Now we will perform the multiplication to find the value of $C$. Using a calculator, we find: $$ C = 2 \cdot \pi \cdot 5 \approx 31.42 $$ (approximately)
The circumference of the circle is $C \approx 31.42$ units.
More Information
The circumference represents the total distance around the circle. The constant $\pi$ (approximately 3.14) is a crucial number in geometry, particularly in circles.
Tips
- Forgetting to multiply by $2\pi$: Always remember to include both constants when using the formula.
- Confusing diameter with radius: Ensure you are using the radius ($r$) and not diameter (which is $2r$).
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