Circles and PiGasometer

Here you can see the cylindrical Gasometer in Oberhausen, Germany. It used to store natural gas which was used as fuel in nearby factories and power plants. The Gasometer is 120m tall, and its base and ceiling are two large circles with radius 35m. There are two important questions that engineers might want to answer:

• How much natural gas can be stored? This is the volumeareadiameter of the cylinder.
• How much steel is needed to build the Gasometer? This is (approximately) the surface areacircumferencediagonal of the cylinder.

Let’s try to find formulas for both these results!