00:01
All right, so we have to do this proof.
00:02
We're given that c is the midpoint of a .e and bd, and we've got to prove that a, b, is parallel to d .e.
00:11
Okay, so we'll start by just kind of diagram and up our picture.
00:16
We have this triangle up here that i'm highlighting in red, and then we have this triangle down here that i'm highlighting in blue.
00:26
All right, so when we start with what we're given, that c is the midpoint.
00:34
So here's our statements.
00:36
I'm going to do two column proof.
00:42
And then here's our reasons over here to the right.
00:46
We draw a little better line there.
00:57
All right.
00:58
So start with what we're given.
01:00
C is the midpoint of these two line segments, a .e and pd.
01:16
That's given.
01:17
Now, since c is in the middle, so if you look at point c right here, it's in the middle of this line segment here.
01:30
So since it's in the middle, that means b, c, and c .d have to be congruent.
01:35
B .c.
01:37
Has to be congruent to c .d.
01:43
And then we could say the same thing since it's in the middle of a from a.
01:48
All the way to e since c's in the middle of those two points, then we can say ac is congruent to ce, and that's by the definition of the midpoint.
02:16
That's what it means to be in the middle.
02:18
It's equidistance from both ends of the line segment.
02:22
All right, so when we say those, when we get those, so now you can mark up our picture, this side right here, c .e, we just said, is congruent to ac, because of the definition of the midpoint.
02:39
We also know that b, c, this side here, is congruent to c .d.
02:49
So that's two sides.
02:51
So we can say these two triangles are now congruent, well, close...