Surface Area: Examples

1. Find the surface area of the paraboloid $z=1+x^{2}+y^{2}$ that lies above the unit circle.

 

Answer:

Because $f_{x}=2x$ and $f_{y}=2y$ you would get the following integral for surface area:
MATH

To make this problem easier to solve we can convert into polar coordinates:
MATH

MATH


2. Find the surface area S of the portion of the hemisphere MATH that lies above the region R bounded by the circle  $x^{2}+y^{2}\leq 9.$

Answer:

First find the partial derivates of $f:$
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We then set up the surface area integral and simplify: MATH


Next we convert to polar coordinates and solve:
MATH


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