00:02
Given ray bd bisects angle a, b, c, and angle a .d.
00:07
Is an acute angle, a .d.
00:10
Is an acute angle, we're going to show that a .b.
00:12
Is not congruent to b .c.
00:15
We're going to start by assuming that a .b.
00:21
Is congruent to b .c.
00:23
This is an assumption.
00:25
Our indirect proofs start with an assumption, and that assumption is the opposite of what we're trying to prove.
00:32
Because if we are able to prove this assumption, then this can't be true.
00:41
Next we have that ray bd, bisects, angle a, b, c.
00:50
This is a given statement.
00:55
Angle a, b, d is congruent to angle c, b, d, and this is the definition of an angle bisector.
01:15
Bd is congruent to bd by the reflexive property.
01:22
Which states that anything is congruent to itself.
01:28
Triangle abd is congruent to triangle cbd by side angle side, as shown in steps one, three, and four.
01:44
Angle b, d, a, is congruent to angle bdc by cpctc.
01:52
Corresponding parts of congruent.
01:54
Triangles are congruent.
01:56
Angle adc is a straight angle...