00:01
Okay, we are told that abcd is a paragraph.
00:05
So put a here, for example, and then go around clockwise like this.
00:10
In order, a, b, c, d.
00:13
Don't do a, c, b, d.
00:15
That's wrong.
00:17
So a, b, c, d like that.
00:18
Here are my two parallel sides, and here are my two parallel sides.
00:24
Then we're told that e is a point on cd, such that b -e -e -e, equals bc.
00:35
So over here somewhere, here is the point e and this length and that length are the same.
00:48
Okay, next i want to prove that abed is cyclic.
00:54
Now cyclic simply means opposite angles add up to 180 degrees.
01:07
This most often occurs in a circle like this.
01:17
Here is my shape with four sides.
01:22
And to be cyclic, a plus b is 180.
01:27
X plus y equals 180...