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Mathematics 17 Online
OpenStudy (anonymous):

How come if three points are collinear then infinitely many planes go through them?

OpenStudy (oaktree):

Hi again. If three points are collinear then we can draw a line that goes through them. And this line can be contained by a plane - infinitely many planes, in fact. Here's a drawing.

OpenStudy (oaktree):

|dw:1377730557139:dw|

OpenStudy (oaktree):

This horrifying rendition of a supernova is actually the following: the point is the line from the side, and each of those lines is a plane. Since you can basically make a circle out of the planes, and we know that there are infinitely many points in a circle, we know there are infinitely many planes that we can draw like this.

OpenStudy (oaktree):

Makes sense? Regardless of my negligible artistic skill?

OpenStudy (anonymous):

so does that mean that many planes can all be in one spot? or is it because planes all extend forever that they'd eventually hit those points?

OpenStudy (anonymous):

or do they all intersect but can't overlap?

OpenStudy (oaktree):

Think about it like this then. What's the intersection of two lines?

OpenStudy (anonymous):

a point

OpenStudy (oaktree):

Okay. And how many lines can go through a single point?

OpenStudy (anonymous):

uhh.. a infinite number of lines

OpenStudy (oaktree):

Right. So similarly, the intersection of two planes is a line, and there are an infinite number of planes that can go through a single line. If you ever get confused, kind of downgrade the problem like that.

OpenStudy (oaktree):

Does THAT make sense?

OpenStudy (anonymous):

yes thank you!!

OpenStudy (oaktree):

Okay. Great.

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