Graphing Polar Equations
Date: 06/02/2002 at 16:45:28 From: Claire Subject: polar equation graph..very hard Hi! I'm in a pre-calculus class and my teacher has assigned us to do these projects where we have to take a polar equation and graph it on a big poster board. My problem is that I don't know how to do it. The equation is (r-3/5)^2 = cos(7 theta). I have a feeling she made up this equation, and no one I've asked has known how to do it, so I would appreciate any help you'd be willing to give me. Thank you so much.
Date: 06/02/2002 at 17:23:35 From: Doctor Ian Subject: Re: polar equation graph..very hard Hi Claire, The general idea is that you choose a value for theta, figure out what the corresponding value of r is, and then plot the point (r,theta) by moving r units along the x-axis, and rotating that distance through theta degrees. Of course, this would be easier if you had something that looked like r = [some function of theta] wouldn't it? So you probably want to solve the equation for r, to get that. Note that you're going to end up taking a square root... and a number always has _two_ square roots, one positive, and one negative. Make sure to deal with both of them! Does this help? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/
Date: 06/04/2002 at 19:29:14 From: Claire Subject: Thank you (polar equation graph..very hard) Hey, Thanks for your assistance. I don't think my partner worded our question very well... but we figured out how to solve the equation. Our problem was that we couldn't see the whole graph on our calculator. We asked our teacher who told us that we can't see the whole graph so we are having fun trying to fill it in. Thanks for the help. The +,- was key. Thanks again, Drew
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.