The diameter of a semicircle is 6 yards. What is the semicircle’s perimeter?
The Correct Answer and Explanation is:
To calculate the perimeter of a semicircle, we need to consider both the curved part (half of the circumference of a full circle) and the straight part (the diameter).
Step 1: Understanding the formula for the perimeter of a semicircle
The perimeter (P) of a semicircle is given by the formula:
[
P = \text{half of the circumference of a circle} + \text{diameter}
]
The circumference (C) of a full circle is calculated by the formula:
[
C = \pi \times d
]
where (d) is the diameter of the circle.
Since a semicircle is half of a circle, the curved part of the perimeter is half of the circumference. Therefore, the perimeter formula becomes:
[
P = \frac{\pi \times d}{2} + d
]
Step 2: Substitute the given values
In this case, the diameter of the semicircle is 6 yards. Plugging this value into the formula:
[
P = \frac{\pi \times 6}{2} + 6
]
[
P = 3\pi + 6
]
Step 3: Approximate the result
Using the approximation ( \pi \approx 3.1416 ), we can substitute this value into the equation:
[
P = 3 \times 3.1416 + 6
]
[
P = 9.4248 + 6
]
[
P \approx 15.4248 \, \text{yards}
]
Step 4: Conclusion
The perimeter of the semicircle is approximately 15.42 yards.
Explanation
The perimeter of a semicircle consists of two parts: the straight part (which is the diameter of the semicircle) and the curved part (which is half the circumference of the full circle). The diameter is straightforward, as it’s directly given in the problem. The curved part requires the use of the formula for the circumference of a circle, adjusted to account for only half of it. By combining these two components, we obtain the total perimeter of the semicircle.