Use the image to answer the question.

An illustration shows a rectangle of unknown height with a circle of radius 3 feet attached to its top left and a circle of radius 3 feet attached to its bottom right.
If the surface area of the net diagram of the right circular cylinder is 395.64 feet2
, find the height of the net diagram. Use 3.14
for π

1 answer

To find the height of the right circular cylinder, we start by using the formula for the surface area of a right circular cylinder:

\[ \text{Surface Area} = 2\pi r(h + r) \]

where:

  • \( r \) is the radius of the base of the cylinder,
  • \( h \) is the height of the cylinder.

In this case, we're given that the radius \( r = 3 \) feet and the surface area is \( 395.64 \) square feet.

Substituting the values into the formula gives us:

\[ 395.64 = 2 \cdot \pi \cdot 3(h + 3) \]

Using \( \pi \approx 3.14 \):

\[ 395.64 = 2 \cdot 3.14 \cdot 3(h + 3) \]

Calculating the left side:

\[ 2 \cdot 3.14 \cdot 3 = 18.84 \]

Now our equation looks like this:

\[ 395.64 = 18.84(h + 3) \]

Dividing both sides by 18.84:

\[ h + 3 = \frac{395.64}{18.84} \]

Calculating the right side:

\[ h + 3 \approx 21 \]

Subtracting 3 from both sides:

\[ h \approx 21 - 3 \] \[ h \approx 18 \]

Thus, the height \( h \) of the cylinder is approximately 18 feet.