Solution: Given: AB = AC ⇒∠ABC=∠ACB⇒∠4+∠1=∠3+∠2⇒∠1=∠2 ∵ ∠3=∠2 The axiom is if equals be subtracted from equals, the remainders are equal

Answer the questions.

Solution:
Given: AB = AC

\Rightarrow ∠ A B C = ∠ A C B \Rightarrow ∠ 4 + ∠ 1 = ∠ 3 + ∠ 2 \Rightarrow ∠ 1 = ∠ 2 (∵ ∠ 3 = ∠ 2)

The axiom is if equals be subtracted from equals, the remainders are equal.