body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} ! You must have JavaScript enabled to use this site.

McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

1. Circles and Circumference

Continue to next subchapter

Exercise 25 Page 720

What is the formula for finding the circumference of a circle?

Radius: 19.74ft
Diameter: 39.47ft

Practice makes perfect

Let's find the radius and the diameter of the circle separately. The circumference C of a circle with radius r is calculated using the formula below. C=2π rFrom the exercise, we know that the circumference of the circle is 124ft. By substituting 124 for C in the formula, we can solve for r.

C=2π r

C= 124

124=2π r

.LHS /2.=.RHS /2.

62 = π r

.LHS /π.=.RHS /π.

62/π = r

Rearrange equation

r = 62/π

Use a calculator

r=19.735212 ...

Round to 2 decimal place(s)

r≈ 19.74

The radius of the circle is approximately 19.74ft. Now, to find the diameter, we can multiply the radius by 2. 2* 62/π ≈ 39.47ft

Subchapter links

Exercises p.719-723