1. find the surface area of a sphere with a circumference of 86 cm. round to the nearest tenth. a. 2,354.2 cm2
b. 1,177.1 cm2
c. 187.3 cm2
d. 13.7 cm2

2. a balloon has a circumference of 16 cm. use the circumference to approximate the surface area of the balloon to the nearest square centimeter. a. 804 cm2
b. 326 cm2
c. 256 cm2
d. 81 cm2

1. Find the surface area of a sphere with a circumference of 86 cm. Round to the nearest tenth.
C = 2πr
r = C / 2π  = 86/2π = 43/π cm
A = 4πr^2 = 4π(43/π)^2 = 2,354.2 cm2

A. 2,354.2 cm2
2. A balloon has a circumference of 16 cm. Use the circumference to approximate the surface area of the balloon to the nearest square centimeter.
C = 2πr
r = C / 2π  = 16/2π = 8/π cm
A = 4πr^2 = 4π(8/π)^2 = 81 cm^2
D. 81 cm2

The rocks expand when there hot/warm  and contract when they are cold.