Question

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Explanation:

Analyze the transition from step 5 to step 6

The statement in step 5 is:

$$ m\angle 1 + m\angle 2 = m\angle 2 + m\angle 3 $$

The statement in step 6 is:

$$ m\angle 1 = m\angle 3 $$

Identify the algebraic operation performed

To go from \(m\angle 1 + m\angle 2 = m\angle 2 + m\angle 3\) to \(m\angle 1 = m\angle 3\), the term \(m\angle 2\) is subtracted from both sides of the equation:

$$ (m\angle 1 + m\angle 2) - m\angle 2 = (m\angle 2 + m\angle 3) - m\angle 2 $$

This simplifies directly to:

$$ m\angle 1 = m\angle 3 $$

Determine the corresponding geometric/algebraic reason

Subtracting the same quantity from both sides of an equation is justified by the Subtraction Property of Equality.

Answer:

1. [?] <blank>Subtraction Property of Equality</blank>