http://www.ck12.org Chapter 10. Perimeter and Area
Asector=120
360
π· 242 A 4 =1
2
(
24
√
3
)
( 12 )
= 192 π = 144√
3
The area of the segment isA= 192 π− 144
√
3 ≈ 353 .8.
In the review questions, make sure you know how the answer is wanted. If the directions say “leave in terms ofπand
simplest radical form,” your answer would be the first one above. If it says “give an approximation,” your answer
would be the second. It is helpful to leave your answer in simplest radical form and in terms ofπbecause that is
the most accurate answer. However, it is also nice to see what the approximation of the answer is, to see how many
square units something is.
Know What? RevisitedThe area of the crust for a deep-dish pizza is 8^2 π− 72 π= 15 π. The area of the crust of
the thin crust pizza is 8^2 π− 7. 52 π=^314 π. One-twelfth of the deep dish pizza has^1512 πor^54 πin^2 of crust. One-fourth
of the thin crust pizza has^3116 πin^2. To compare the two measurements, it might be easier to put them both into
decimals.^54 π≈ 3. 93 in^2 and^3116 π≈ 6. 09 in^2. From this, we see that one-fourth of the thin-crust pizza has more crust
than one-twelfth of the deep dish pizza.
Review Questions
Fill in the following table. Leave all answers in terms ofπ.
TABLE10.2:
radius Area circumference- 2
- 16 π
- 10 π
- 24 π
- 9
- 90 π
- 35 π
8.^7 π - 60
- 36
Find the area of the blue sector or segment in
⊙
A. Leave your answers in terms ofπ. You may use decimals or
fractions in your answers, but do not round.