# Math Is Fun Forum

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## #1 2023-02-20 04:42:38

mathdrop
Member
Registered: 2022-03-07
Posts: 73

### Reflecting point on plane through origin

I have the normal vector of a reflection-plane which goes through the origin.

How to reflect a point on this plane ?

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## #2 2023-02-20 22:53:49

Bob
Registered: 2010-06-20
Posts: 9,633

### Re: Reflecting point on plane through origin

I'm not clear what you want here.

If you have the normal vector then you also have the equation of the plane.

Is your object point anywhere in 3D or is it on the normal.  Actually this doesn't matter as the normal can be moved parallel to go through any point.  If N is a point on the normal and A is where it cuts the plane then find the vector NA and hence AB where B is the image point and NA = AB.

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

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## #3 2023-02-21 11:26:01

mathdrop
Member
Registered: 2022-03-07
Posts: 73

### Re: Reflecting point on plane through origin

That's, what I needed.

Now I'll go refreshing my memory about the single steps.

(The point is anywhere in 3D.)

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