Finding the scalar equation of a plane

In summary, to find the equation of a plane that goes through points P, Q, and R, you can use the cross product of any two of these points to get a normal vector. It doesn't matter which point you choose for x0, y0, or z0 in the equation of the plane.
  • #1
Calpalned
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6

Homework Statement


Find the equation of the plane that goes through points P, Q and R. P = (3, -1, 2), Q = (8, 2, 4) and R = (-1, -2, -3)

Homework Equations


Eq of plane
0 = a(x - x0) + b(y - y0) + c(z - z0)

The Attempt at a Solution


In order to find vector normal to the plane, my teacher took the cross product of PQ X PR. Would I still get the correct normal vector if I take the cross product of PQ X QR? Finally, when I plug in the numbers to the equation in "

Homework Equations

", does it matter which point I choose (P, Q or R) for x0, y0, or z0? Thank you.
 
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  • #2
Calpalned said:

Homework Statement


Find the equation of the plane that goes through points P, Q and R. P = (3, -1, 2), Q = (8, 2, 4) and R = (-1, -2, -3)

Homework Equations


Eq of plane
0 = a(x - x0) + b(y - y0) + c(z - z0)

The Attempt at a Solution


In order to find vector normal to the plane, my teacher took the cross product of PQ X PR. Would I still get the correct normal vector if I take the cross product of PQ X QR? Finally, when I plug in the numbers to the equation in "

Homework Equations

", does it matter which point I choose (P, Q or R) for x0, y0, or z0? Thank you.
Yes, you can use PQ×QR or, for that matter, PR×QR . Each gives a vector which is normal to the plane.

No, it doesn't matter which point you use. Try more than one and compare results.
 
  • #3
SammyS said:
Yes, you can use PQ×QR or, for that matter, PR×QR . Each gives a vector which is normal to the plane.

No, it doesn't matter which point you use. Try more than one and compare results.

Thank you
 

FAQ: Finding the scalar equation of a plane

What is a scalar equation of a plane?

A scalar equation of a plane is a linear equation that represents a plane in three-dimensional space. It is in the form of ax + by + cz + d = 0, where a, b, and c are the coefficients of the variables x, y, and z, and d is a constant.

How is a scalar equation of a plane different from a vector equation?

A scalar equation of a plane only uses linear combinations of the variables x, y, and z, while a vector equation uses the cross product of two vectors to represent the plane. A scalar equation is also simpler and easier to work with in most cases.

How is a scalar equation of a plane determined?

A scalar equation of a plane is determined by finding the normal vector of the plane, which is a vector perpendicular to the plane, and using it to form the equation ax + by + cz + d = 0. The coefficients a, b, and c can be determined by using the coordinates of three points on the plane.

Can a scalar equation of a plane be used to graph the plane?

Yes, a scalar equation of a plane can be used to graph the plane by solving for one of the variables and treating the other two variables as parameters. This will result in a linear equation in two variables, which can be graphed on a two-dimensional coordinate plane.

Are there any special cases when finding the scalar equation of a plane?

Yes, there are special cases when finding the scalar equation of a plane. For example, if the plane is parallel to one of the coordinate axes, the corresponding coefficient in the equation will be zero. Also, if the plane passes through the origin, the constant term d will be zero.

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