How many y− intercepts can a graph of a vertical parabola have? Why?
2 answers:
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I think this is how you do it. Hope this helps!!
The cylinder is symmetric across the plane 
, so we need only consider half of the cut-out region.
This region can be parameterized by
with
and 
. Then the area of this half is given by the surface integral
Doubling this gives a total area of 72.
This region can be parameterized by
with
Doubling this gives a total area of 72.