00:01
So we have two parameterized lines here.
00:03
We want to see whether or not they are secretly the same line.
00:08
To do that, i'm going to write them out by separating out the constant term and the directional term as follows.
00:17
Take out all the constants from r1.
00:19
That's 5i plus 1j plus 0k, not equals, but plus negative 3i plus j plus 2k times t.
00:35
So i've taken out all of the the t stuff and put it over here and the constant stuff and put it on.
00:41
Do a similar trick for r2.
00:46
That'll be 2i plus 2j plus 3k plus 6i minus 2j, that's an i, minus 4k times t.
01:08
We see these two directions are parallel because one is just negative, this bottom one is negative two times the top one, and then it's just a matter of showing whether they have a point in common, because two parallel lines with a point in common are the same line.
01:27
So let's check that real quick.
01:29
If you set t equal to zero, then we can see very clearly that 5i plus j is in r1.
01:37
It looks equal to r1 of zero.
01:41
Let's see if it's equal to r2 of any value of t.
01:46
In particular, we can have this as a system of linear equations...