I've included a picture stating the problem. How do I approach this? I recognize that is the equation of a circle, but that's about all I have.
Follow Math Help Forum on Facebook and Google+
Originally Posted by Ares_D1 I've included a picture stating the problem. How do I approach this? I recognize that is the equation of a circle, but that's about all I have. When you rotate the curve about the z axis you get the surface (in cylindrical polar coords). Since , then , giving your answer.
Originally Posted by Danny When you rotate the curve about the z axis you get the surface (in cylindrical polar coords). Since , then , giving your answer. Thanks for the help Danny, but I'm not sure I follow that last bit. Could you explain further how and , and how, from that, you end up with ?
Originally Posted by Ares_D1 Thanks for the help Danny, but I'm not sure I follow that last bit. Could you explain further how and , and how, from that, you end up with ? and are polar coordinates - an alternate way to describe a point in 2D. Since
By the way, the statement " lies in the xy-plane" is incorrect. Since you are then to rotate around the z-axis, I imagine it was supposed to be "lies in the xz-plane".
View Tag Cloud