I'm not sure how to solve this.
SA = 2B + AL (surface area = 2 base areas + lateral area)
Let r = radius, and h = height
308 = 2pi r^2 + 2pi r h = 6pi r^2, since h = 2r
Solve for r,
r = sqrt(308/(6pi))
h = 2r = 8.085 cm <==Answer
I'm not sure how to solve this.
SA = 2B + AL (surface area = 2 base areas + lateral area)
Let r = radius, and h = height
308 = 2pi r^2 + 2pi r h = 6pi r^2, since h = 2r
Solve for r,
r = sqrt(308/(6pi))
h = 2r = 8.085 cm <==Answer
The area of a single end = (pi)r^2. The area of both ends = twice this, or 2(pi)r^2.
The area of the circular surface = 2(pi)rh, or 2(pi)r(2r) or 4(pi)r^2.
Combine both ends and the curved surface, total area = 2(pi)r^2 + 4(pi)r^2.
(A/(6(pi)))^(1/2) = r.
(308 cm^{2}/(6(pi)))^(1/2) = 4.04 cm = r. The height is 2x the radius, or 8.08 cm
A cylinder has the SA of 308 cm^2. The height is two times greater than the radius. What is the height of the cylinder?
Volume of cylinder = (area of base)(height)
Volume of cylinder = ((pi)r^2)(height)
Let h = height
then
h/2 = radius
substitute above into:
Volume of cylinder = ((pi)r^2)(height)
308 = ((3.14)(h/2)^2)(h)
308 = ((3.14)(h^2/4))(h)
308 = (.785h^2)(h)
308 = .785h^3
392.357 = h^3
take cube root of both sides to get:
7.32 cm = h (height)
Comments
Bill, you used the 308 cm^{2} as volume instead of surface area.