Unequal angles are not opposite to vertex angles Is this proposition true? Give reasons

Unequal angles are not opposite to vertex angles Is this proposition true? Give reasons

Set up
To the contrary:
If angle 1 = angle 2, they may be opposite vertex angles
Then 180 - Jiao 1 = 180 - Jiao 2 (the complements of the same angle are equal), Jiao 1 = Jiao 2, which is inconsistent with the proposition
So the proposition holds
In fact, this proposition is equivalent to "equal angle is opposite vertex"

Elden Ring Premiere

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