# How did they get these bounds for this double integral?

• November 6th 2010, 01:09 PM
Evan.Kimia
How did they get these bounds for this double integral?
heres a problem from my textbook. How did they figure out those bounds for theta? On an exam i wont be able to use a calculator that graphs polar coords, and i should know how to do this anyways. Thanks

http://i55.tinypic.com/bfjoz8.png
• November 6th 2010, 01:11 PM
mr fantastic
Quote:

Originally Posted by Evan.Kimia
heres a problem from my textbook. How did they figure out those bounds for theta? On an exam i wont be able to use a calculator that graphs polar coords, and i should know how to do this anyways. Thanks

http://i55.tinypic.com/bfjoz8.png

It's obvious where the bounds have come from. Are you asking how $x^2 + y^2 = 2x$ is converted to a polar equation?
• November 6th 2010, 01:14 PM
Evan.Kimia
I understand how the bounds for r are set by converting http://www.mathhelpforum.com/math-he...01dddb08b5.png to polar coords but im not sure howe the bounds for theta (the -pi/2 to pi/2) are figured out.
• November 6th 2010, 01:35 PM
mr fantastic
Quote:

Originally Posted by Evan.Kimia
I understand how the bounds for r are set by converting http://www.mathhelpforum.com/math-he...01dddb08b5.png to polar coords but im not sure howe the bounds for theta (the -pi/2 to pi/2) are figured out.

The polar angle associated with (2, 0) is 0.

The polar angles associated with (0, 0) are -pi/2 and pi/2.