Answer:
It would help to have the cone area formula:
Area = PI * radius * slant height
Let's say the height is 12cm radius is 5 cm
which makes the (slant height)^2 = 12^2 + 5^2 = 169
slant height = 13
and surface area = PI * 5 * 12 = 188.4955592154
If radius = 10 then (slant height)^2 = 12^2 + 10^2 = 244
slant height = 15.6204993518
surface area = PI * 10 * 15.62 = 376.99
376.99 / 188.4955 = 2
So, if radius is doubled, surface area is doubled.
Source: http://www.1728.org/volcone.htm
Step-by-step explanation:
