# Problem Finding a Parametrization for a Circle

• Oct 27th 2012, 08:31 AM
Beevo
Problem Finding a Parametrization for a Circle
Hey guys,
I am having a little difficulty solving a problem. It says: Find a parametrization for the circle having radius 3 and center (3, 4, −5) that lies in a plane parallel to the zx-plane.

Well, I initially just combined the center with the radius to get parametric equations of :
x = 3 + 3cost, y = 4, z = -5 +3sint, but this appears to be wrong. Can anyone tell me what I am doing wrong.

Any help and feedback is greatly appreciated, thanks.
• Oct 27th 2012, 08:44 AM
TheEmptySet
Re: Problem Finding a Parametrization for a Circle
Quote:

Originally Posted by Beevo
Hey guys,
I am having a little difficulty solving a problem. It says: Find a parametrization for the circle having radius 3 and center (3, 4, −5) that lies in a plane parallel to the zx-plane.

Well, I initially just combined the center with the radius to get parametric equations of :
x = 3 + 3cost, y = 4, z = -5 +3sint, but this appears to be wrong. Can anyone tell me what I am doing wrong.

Any help and feedback is greatly appreciated, thanks.

You have a correct parameterization of a circle. The only thing I can think of is that they asked for it to have a certain orientation. The circle is oriented counter clockwise around the unit vector $\displaystyle \mathbf{j}$ in the plane $\displaystyle y=4$
• Oct 27th 2012, 08:49 AM
Beevo
Re: Problem Finding a Parametrization for a Circle
Quote:

Originally Posted by TheEmptySet
You have a correct parameterization of a circle. The only thing I can think of is that they asked for it to have a certain orientation. The circle is oriented counter clockwise around the unit vector $\displaystyle \mathbf{j}$ in the plane $\displaystyle y=4$

If it is oriented counter clockwise around the unit vector, how would it change the parametrization? Would it simply change the signs of my current parametrization?