Method to parameterize circles in R3 laying in a plane

In summary, to parametrize a circle of radius r at centre (a,b,c) laying on a plane, one method is to start with a circle of radius r centered at the origin in the xy-plane, rotate it to lie in the plane parallel to the given plane, and then translate it to be centered at (a,b,c). Another method is to find two unit vectors perpendicular to the plane's normal vector and perpendicular to each other, and use the equation R(t) = <a,b,c> + r*u*cos(t) + r*v*sin(t).
  • #1
dispiriton
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Homework Statement


In general how do i parametrize a circle of radius r at centre (a,b,c) laying on a plane? E.g. (x + y + z = 6)


Homework Equations





The Attempt at a Solution

 
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  • #2
You could start with a circle of radius r centered at the origin that lies in the xy-plane. Then apply a rotation so that it lies in the plane parallel to the given plane. Finally, translate it so it's centered at (a,b,c).
 
  • #3
Vela has given you one method. Another is to find two unit vectors u and v that are perpendicular to the plane's normal vector N and perpendicular to each other. Then use

[tex]R(t) = \langle a,b,c\rangle +r \vec u \cos(t) + r\vec v \sin(t)[/tex]
 

Related to Method to parameterize circles in R3 laying in a plane

1. How are circles in R3 parameterized?

In R3, circles can be parameterized using the following equations:

x = cx + rcos(t)

y = cy + rsin(t)

z = cz

where (cx, cy, cz) is the center of the circle and r is the radius. The parameter t ranges from 0 to 2π.

2. Can circles in R3 be parameterized if they do not lie in a plane?

No, circles in R3 can only be parameterized if they lie in a plane. This is because the equations used to parameterize circles in R3 assume that the z-coordinate remains constant, which is only true for circles lying in a plane.

3. What is the significance of parameterizing circles in R3?

Parameterizing circles in R3 allows for a systematic way of representing and manipulating circles in three-dimensional space. It also simplifies calculations involving circles, such as finding intersections with other objects or calculating the length of an arc.

4. Is there a different method for parameterizing circles in R3 with a non-zero z-coordinate?

Yes, there is a different method for parameterizing circles in R3 with a non-zero z-coordinate. It involves using the equations:

x = cx + rcos(t)

y = cy + rsin(t)

z = cz + h

where (cx, cy, cz) is the center of the circle, r is the radius, and h is the desired height of the circle above the xy-plane.

5. How can the parameterization of a circle in R3 be used in real-world applications?

The parameterization of circles in R3 can be used in various real-world applications, such as computer graphics, physics, and engineering. For example, in computer graphics, circles can be represented and manipulated using their parameterization, allowing for the creation of 3D images and animations. In physics and engineering, the parameterization of circles can be used to model and analyze circular motion in three-dimensional space.

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