Is 2i + j + 3k the Normal Vector of Plane CDPQ?

BvUIn summary, the normal vector of plane ABQP is -2i - j + 3k, and to prove that 2i + j + 3k is the normal vector of plane CDPQ, we can use the formula for the vector product, which states that ||A||*||B||*sin(theta)*n, where n is the unit vector perpendicular to both A and B. In the plan view, the normal vectors for both planes should have a similar orientation, with possible symmetries between them.
  • #1
songoku
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Homework Statement
The planes ABCD and EFGH are parallel to the horizontal surface represented by the xy-plane. The triangles APD and BQC are congruent isosceles triangles and the lengths of the pillars AE, BF, CG, and DH are of the same height. The equation of the plane ABQP is given by -2x-y+3z = 2 and the point P has position vector 4i + 2j + 4k.

Explain why plane CDPQ is perpendicular to 2i + j + 3k. Hence show that the equation of the plane CDPQ is 2x + y + 3z = 22
Relevant Equations
Equation of plane: r . n = c
1661086020781.png


I know the normal of plane ABQP is -2i - j + 3k but I don't know how to prove that 2i + j + 3k is the normal vector of plane CDPQ

Thanks
 
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Hi, hope you are in the fullest of your sprits!
To find the normal, you can use the vector product
If you don't know what that is, then

A \times B=\left\| A \right\| \left\| B \right\| \sin \theta n

where ||A|| and ||B|| are magnitudes of vectors A and B respectively
 
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  • #3
Cuckoo Beats said:
Hi, hope you are in the fullest of your sprits!
To find the normal, you can use the vector product
If you don't know what that is, then

A \times B=\left\| A \right\| \left\| B \right\| \sin \theta n

where ||A|| and ||B|| are magnitudes of vectors A and B respectively
The formula shown is somewhat unclear, as it looks like the last factor is ##\sin (\theta n)##. In fact, the formula should be as follows:
$$\vec A \times \vec B = \left(|\vec A| |\vec B| \sin(\theta)\right) \vec n$$
where ##\vec n## is the unit vector that is perpendicular to both ##\vec A## and ##\vec B##.
 
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Cuckoo Beats said:
Hi, hope you are in the fullest of your sprits!
Hello @Cuckoo Beats ,
:welcome:
 
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  • #5
songoku said:
I know the normal of plane ABQP is -2i - j + 3k but I don't know how to prove that 2i + j + 3k is the normal vector of plane CDPQ

One way to think about this problem is to look at the plan view.

If the normal vector to plane ABQP is -2i - j + 3k, what does that normal vector look like in the plan view?

What does the normal vector to CDPQ look like in the plan view? How that vector relate to the previous normal vector you drew? (Think about any kind of symmetries that should be there.)
 
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  • #6
I think I get the hint.

Thank you very much Cuckoo beats, Mark44, SammyS, olivermsun
 

FAQ: Is 2i + j + 3k the Normal Vector of Plane CDPQ?

What is a normal vector of a plane?

A normal vector of a plane is a vector that is perpendicular to the surface of the plane. It is used to determine the orientation and direction of the plane.

How is the normal vector of a plane calculated?

The normal vector of a plane can be calculated by finding the cross product of two non-parallel vectors that lie on the plane. Another method is to use the coefficients of the plane's equation to determine the direction of the normal vector.

What is the significance of the normal vector in plane geometry?

The normal vector is important in plane geometry because it helps determine the angle of incidence and reflection of light rays on the plane's surface. It is also used in calculating the distance of a point from the plane and in finding the equation of a line perpendicular to the plane.

Can a plane have multiple normal vectors?

No, a plane can only have one unique normal vector. However, there can be an infinite number of vectors that are perpendicular to the plane's surface.

How is the normal vector of a plane used in 3D graphics?

In 3D graphics, the normal vector is used to determine the shading and lighting of objects on a plane. It helps create a realistic and visually appealing image by simulating the way light bounces off surfaces. It is also used in rendering techniques to create smooth surfaces and shadows.

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