00:01
So here we want to find a plane that passes through these two given points and is perpendicular to the given plane.
00:08
So remember, what we need for a plane is a normal vector, or equivalently just two vectors in the plane.
00:17
From two vectors in the plane, we can take their cross product to produce a normal vector.
00:22
So we can get one vector just by the vector that goes from p1 to p2, which we get just by subtracting the coordinates.
00:39
Okay, and we need another vector.
00:43
So we have another piece of information we need to use.
00:47
So the normal vector for this plane, maybe i'll call it v, can just be right off as 4 minus 1, 2.
00:59
Okay, and so saying that our plane, so let's say here's my plane that's given to me.
01:07
Okay, and so my normal vector, v is like that.
01:11
And we're saying that the plane we want is perpendicular to this one.
01:18
So if you try and draw a picture of a perpendicular plane, it would look something like this.
01:30
Okay, and what we notice about it is that this normal vector of the perpendicular plane actually lies inside the plane we want.
01:43
So this is another vector in our plane...