Let's find the perimeter of this semicircle. The straight side is the diameter of a full circle. We know that the radius is 15 inches. According to the definitions, the diameter is twice the radius. Let's multiply the radius by 2!
15* 2 = 30
This means that the straight side is 30 inches. The distance around the curved part is one-half the circumference of the circle. The circumference C of a circle with radius r is calculated using the formula below.
C=2Ï€ r
From the figure, we know that the radius of the circle is 15 inches. We can substitute 15 for r in the formula and then calculate C. We will use 3.14 as an estimate for π.
The circumference of the full circle is approximately 94.2 inches. We divide this circumference by 2 to find the distance around the curved part.
94.2÷ 2 = 47.1
Finally, we can add 47.1 and the straight side 30 to find the perimeter.
47.1+30=77.1
We found that the perimeter is approximately 77.1 inches.
Extra
More About Circles!
Are you interested in learning more about circles? Our Mathleaks original content can teach you all about them! Check out the following resources to see real-world uses for circumference and area, how circles compare to other shapes and why, as well as some higher level topics that you can look forward to learning about in Geometry and Algebra 2.
