Question

Use the given circumference to find the surface area of each spherical object. Round your answer to the nearest whole number.

pincushion with C=8 cm

Answer 1

Circumference = 2(pi)r = 8 cm. r = 8 / (2pi)

Surface area of sphere = 4(pi)r^2 = 4(pi) * 64 / (4pi^2) = 64 / pi = ? cm^2

Answer 2

\[C=2\pi r\]
\[8=2\pi r\]
\[\frac{ 8 }{ 2\pi }=\frac{ 2\pi r }{2 \pi }\]
\[1.27=r\]
\[SA=4\pi r^2\]
\[SA=4 \pi (1.27)^2\]
\[SA=20.27\]
\[SA \approx 20 cm ^3\]

Answer 3

sorry i meant 20 cm ^3

Answer 4

Yes, area rounded to the nearest whole number is: 20 cm^2

Answer 5

hooray :D

Answer 6

ty @ranga

Answer 7

yw.