Find the equation of the plane given a point and two planes

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 3K views
sawdee
Messages
12
Reaction score
0
I've done a question similar to this, however this one has no complete equations i can solve for.

Determine the equation of the plane that passes through (1,3,8) and is perpendicular to the line of intersection of the planes 3x−2z+1=0 and 4x+3y+7=0.

I know to take the cross product of the two normals to get my new direction vector, but I am stuck at that point. What form should this be written in and further, can I use the given point?
 
Last edited by a moderator:
Physics news on Phys.org
sawdee said:
I've done a question similar to this, however this one has no complete equations i can solve for.
You're asked to find the equation of the plane with the given point

sawdee said:
Determine the equation of the plane that passes through (1,3,8) and is perpendicular to the line of intersection of the planes 3x−2z+1=0 and 4x+3y+7=0.

sawdee said:
I know to take the cross product of the two normals to get my new direction vector,
Yes, that will work.

sawdee said:
but I am stuck at that point. What form should this be written in and further, can I use the given point?
There are several different forms of the equation of a plane, so unless the grader is especially particular, it doesn't matter much what form you use.
You have to use the given point in order to get a unique plane. If N is the direction of the intersection of the given planes (and hence is normal to the plane you want), then the equation of the plane is ##n_1(x - 1) + n_2(y - 3) + n_3(z -8) = 0##, where ##\vec N = <n_1, n_2, n_3>##.
 
  • Like
Likes   Reactions: Greg Bernhardt