Question

A right cylinder has radius 9 cm and height 12 cm. If the radius and height are tripled, what happens to the surface area? A. The surface area is multiplied by 9. B. The surface area is multiplied by 6. C.The surface area is multiplied by 1/3. D. The surface area is tripled.

Answer 1

the formula for surface area is
A= 2
`\pi` rh + 2
`\pi` r
`x^(2)`
The cylinder not trippled
SA = 1187.52
Trippled
SA= 10687.7
so the answer is A. multiplied by 9

Answer 2

cylinder surface area (original) =2pir^2+2pirh
if height is trippled and radius is tripple then

new area=2pi(3r^2)+2pi(3r)(3h)
new area=2pi9r^2+2pirh9
new area=9(2pir^2)+9(2pirh)
new area=9(2pir^2+2pirh)
remember that 2pir^2+2pirh=original area
new are=9(original area)

therefor the surface area is multiplied by 9