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.

Glencoe Math: Course 2, Volume 2

GM

Glencoe Math: Course 2, Volume 2 View details

2. Area of Circles

Continue to next subchapter

Exercise 29 Page 629

The area of a semicircle equals half the product of π and the square of its radius.

About 64.3in.^2

Practice makes perfect

Let's consider the given semicircle.

Circle

We want to find the area of the semicircle. Recall that the area A of a semicircle equals half the product of π and the square of its radius r. A = 1/2 π r^2 Since the diameter of the semicircle is 12.8 inches, the radius of the semicircle is ( 12* 12.8) inches or 6.4 inches. Let's calculate the area using this information. Remember, we are asked to use 3.14 as an estimation of π.

A = 1/2 π r^2

r= 6.4

A = 1/2 π ( 6.4^2)

π ≈ 3.14

A ≈ 1/2 (3.14) (6.4^2)

Calculate power

A ≈ 1/2 (3.14) (40.96)

Write as a decimal

A ≈ 0.5 (3.14) (40.96)

Multiply

A ≈ 64.3072

Round to 1 decimal place(s)

A ≈ 64.3

We found that A ≈ 64.3, which means that the area of the semicircle is about 64.3 square inches.

Subchapter links

Guided Practice p.626

Independent Practice p.627-628

H.O.T. Problems p.628

Standardized Test Practice p.628-630

Extra Practice p.629

Common Core Review p.630