Question 997600
Does the cylinder have caps on the ends or is it so if you look down one end you can see clear through the other side?
Diameter of 12. The perimeter is:
2rPi and since 2 times radius is the same as diameter, we take a short cut:
12Pi= 37.7 and
37.7*9= 339.30 is the area of one side of the cylinder, and since the problem says "total surface area" we should multiply this times 2: 678.6 is the total area of the cylinder with open ends. 
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If you find out you need the end caps add the result below to 678.6:
Area of a circle: r^2Pi
6^2Pi
36Pi= 113.1 The cylinder has two ends, that's two caps inside and out, four surfaces, so:
113.1*4= 452.4