Find the circumference of the circle rounded to the nearest whole number.
Understand the Problem
The question is asking to calculate the circumference of a circle given its radius of 4 cm and round the answer to the nearest whole number. The circumference can be calculated using the formula C = 2πr.
Answer
The circumference is approximately $25 \, \text{cm}$.
Answer for screen readers
The circumference of the circle is approximately $25 , \text{cm}$.
Steps to Solve
-
Identify the Formula for Circumference
The circumference of a circle can be calculated using the formula:
$$ C = 2\pi r $$ -
Substitute the Radius into the Formula
Given the radius $ r = 4 , \text{cm}$, substitute this value into the formula:
$$ C = 2\pi(4) $$ -
Calculate the Circumference
Now perform the multiplication:
$$ C = 8\pi $$ -
Approximate the Value of π
Using an approximate value for π, we can calculate:
$$ C \approx 8 \times 3.14 $$ -
Finish the Calculation
Perform the multiplication:
$$ C \approx 25.12 , \text{cm} $$ -
Round to the Nearest Whole Number
Round $25.12$ to the nearest whole number to get:
$$ C \approx 25 , \text{cm} $$
The circumference of the circle is approximately $25 , \text{cm}$.
More Information
The circumference represents the distance around the circle. For a circle with a radius of 4 cm, the calculation reveals how much space it covers around the outer edge.
Tips
- Forgetting to use the correct radius: Always ensure that the radius you are using corresponds to the circle in question.
- Incorrect approximation of π: Sometimes, students may use a rounded value of π that is not precise enough, leading to inaccurate results. It's best to use at least $3.14$.
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