00:02
Alright, this time we are given an equal angular triangle and we just want to prove that that's also equilateral, which isn't too too bad it takes a little bit of explaining.
00:19
Okay, so we start with our given we say angle d is congruent to angle e is congruent to angle f and that's given and i just picked the triangle from the actual corollary that this came from, you can pick whatever letters you want.
00:39
Not a big deal.
00:41
Okay, so first step, since the first two given are de and ef, let's start there.
00:48
So how can we show d .e .e .f.
00:50
Are congruent.
00:52
Well, since the angles opposite to them are congruent, we can use the converse of the isocise triangle theorem to show that these two sides need to be congruent.
01:01
So we can say d .e.
01:07
Is congruent to e .f.
01:13
And this is the converse, isosceles triangle theorem.
01:22
Let's number our steps just in case.
01:26
So step two, this is step one.
01:30
Okay.
01:31
And then we can do that again for ef and fd.
01:36
Especially if we could, well, let's pick blue.
01:38
I like blue.
01:39
So we say ef and fd.
01:45
So these two have to be the same for the exact same reason.
01:48
Conversi sossi's triang there.
01:50
So step three, we can say ef, that's an f promise, is congruent to d .f for the same reason...