Proof: Angle Addition Theorem

Let's prove the following theorem:

Proof:

Proof Table

#	Claim	Reason
1	((m∠ABX) + (m∠XBC) < 180) or ((m∠ABX) + (m∠XBC) = 180)	if point X lies in interior of ∠ABC, then ((m∠ABX) + (m∠XBC) < 180) or ((m∠ABX) + (m∠XBC) = 180) (Interior Property (Converse))
2	m∠ABC = (m∠ABX) + (m∠XBC)	if ((m∠ABX) + (m∠XBC) < 180) or ((m∠ABX) + (m∠XBC) = 180), then m∠ABC = (m∠ABX) + (m∠XBC) (Angle Addition Postulate)

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