A white cylindrical silo has a diameter of $30$ feet and a height of $80$ feet. A red stripe with a horizontal width of $3$ feet is painted on the silo, as shown, making two complete revolutions around it. What is the area of the stripe in square feet?
The provided solution says that
The cylinder can be "unwrapped" into a rectangle, to get a stripe that is a parallelogram with base $3$ and height $80$.
However, I don't understand how the height of the stripe can be eighty. The distance from the top of the cylinder to the bottom is $80$ feet as given, so how can a winded stripe that goes around be also $80$ feet? Isn't the shortest distance, $80$ ft, simply from the top to the bottom? How does a winded spiral also become $80$ feet?