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A manufacturing firm wants to package its product in a cylindrical container 2 ft. high with surface area 6piπ ft^2. What should the radius of the circular top and bottom​ be?

What is the radius?


__ ft.

2 Answers

5 votes

To find the radius of the cylindrical container, we need to consider the formula for the surface area of a cylinder. The surface area (SA) of a cylinder can be calculated using the formula:

SA = 2 * π * r^2 + 2 * π * r * h

Where:
r is the radius of the circular top and bottom,
h is the height of the cylinder,
and π (pi) is a mathematical constant approximately equal to 3.14159.

We know the total surface area is 6π square feet and the height (h) is 2 feet. Let’s plug these values into the formula and solve for the radius (r).

Given:
SA = 6π
h = 2

Using the surface area formula:
6π = 2 * π * r^2 + 2 * π * r * 2
6π = 2πr^2 + 4πr

Now, let's solve this equation for r:

First, we can simplify by dividing each term by 2π to reduce the equation:
3 = r^2 + 2r

We now have a quadratic equation:
0 = r^2 + 2r - 3

This is in the standard quadratic form of ax^2 + bx + c = 0, where:
a = 1, b = 2, and c = -3.

Next, we will solve for r using the quadratic formula:
r = (-b ± √(b² - 4ac)) / (2a)

Plugging in the values from our equation, we get:
r = (-2 ± √(2² - 4*1*(-3))) / (2*1)
r = (-2 ± √(4 + 12)) / 2
r = (-2 ± √16) / 2
r = (-2 ± 4) / 2

This equation has two solutions:
r1 = (-2 + 4) / 2 = 2 / 2 = 1
r2 = (-2 - 4) / 2 = -6 / 2 = -3

Since a radius can't be negative, we discard the negative solution. Therefore, the radius of the circular top and bottom of the cylindrical container is 1 foot.

User Steven Evers
by
6.1k points
3 votes

Answer:

1 ft

Explanation:

If r is the radius of the circular top and bottom and h is the height of the cylinder, then the surface area of the cylinder is


A=2\pi r^2+2\pi rh.

In your case, h=2 ft and
A=6\pi\ft^2.

Hence,


6\pi =2\pi r^2+2\pi r\cdot 2,\\ \\6\pi=2\pi(r^2+2r),\\ \\r^2+2r=3,\\ \\r^2+2r-3=0,\\ \\D=2^2-4\cdot (-3)=4+12=16,\\ \\r_(1,2)=(-2\pm 4)/(2)=-3,\ 1.

The radius cannot be negative, then r=1 ft.


A manufacturing firm wants to package its product in a cylindrical container 2 ft-example-1
User Maestro
by
4.3k points