# Line plane intersect within boundaries

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• November 10th 2010, 08:08 AM
yellowFattyBEan
Line plane intersect within boundaries
Hi

I have managed to calculate where a line intersects a plane by substituting the parametric equations of a line into the equation of a plane.

If a plane can be defined as infinite and a line must intersect the plane at some point unless paralell to the line and not colinear, how can you determine if a point of intersection lies within the visible defined boundaries of the plane?
• November 10th 2010, 09:34 AM
Plato
Quote:

Originally Posted by yellowFattyBEan
If a plane can be defined as infinite and a line must intersect the plane at some point unless paralell to the line and not colinear, how can you determine if a point of intersection lies within the visible defined boundaries of the plane?

A plane has no "visible defined boundaries".
• November 10th 2010, 09:56 AM
yellowFattyBEan
I'm sorry, I should have explained it a bit clearer.

I need to find if a point lies within the boundaries of 4 vectors, creating a perimeter on the plane.
• November 10th 2010, 10:58 AM
Plato
Quote:

Originally Posted by yellowFattyBEan
I'm sorry, I should have explained it a bit clearer.
I need to find if a point lies within the boundaries of 4 vectors, creating a perimeter on the plane.

Suppose you have four co-planar points that form a convex quadrilateral.
You want the point to be in the interior of one pair of opposite angle.
Example suppose that $PQRS$ is a convex quadrilateral.
Then $\angle SPQ\;\& \,\angle QRS$ are opposite angles.
So the point should be in the interior of both angles.
• November 18th 2010, 03:35 AM
yellowFattyBEan
Yeah, Thats what I'm trying to find out.