00:01
All right, so for number 13, we're given the fact that we're trying to see if this is, first of all, a trapezoid, and if it is a trapezoid, then is it going to be isosceles.
00:10
So we need to, first of all, check the slope.
00:13
So we're going to check slopes first, opposite slopes, and see if they're parallel.
00:20
So checking the opposite slopes mean we're going to check a, b, along with c, d.
00:25
So we've got a, b, slope versus the d -c slopes.
00:31
So slope is taking your y's and subtracting them over your x's being subtracted.
00:36
So we've got three takeaway negative one.
00:40
That's become a plus.
00:41
And then we've got negative three take away a negative four.
00:47
And that's going to become a plus.
00:50
So that's four over one, which is just four.
00:54
Then we're going to go check dc.
00:56
So dc is three take away negative one.
01:01
Change that to a plus.
01:02
And two take away five.
01:05
So it turns out that this is going to be a four over negative three.
01:12
So because they're not equal, these guys are not parallel.
01:17
So that doesn't necessarily mean that this isn't a trapezoid.
01:22
We still just have to check and see about ad and b .c.
01:26
Because then that would mean that a, b, and the d .c could potentially be our isosceles parts.
01:30
So we're going to go check the slopes of, we'll do that over here.
01:37
We'll check the slopes of ad versus the slopes of bc.
01:42
So ad, you have 3 minus 3 over negative 3 minus 2.
01:49
So i'm just going to say the top is 0, so the whole slope is zero.
01:53
So that saves us a little bit of time.
01:54
And then we're going to check bc.
01:57
So bc is negative 1.
02:01
Take away negative 1, that's going to change to a negative 1 plus 1...