Question

which is a true statement about the diagram?
○ $m\angle5 + m\angle6 = m\angle1$
○ $m\angle3 + m\angle4 + m\angle5 = 180^circ$
○ $m\angle1 + m\angle2 = 180^circ$
○ $m\angle2 + m\angle3 = m\angle5$

Explanation:

Step1: Analyze angle sum of triangle

Angles 3, 4, 5 form a triangle, so their sum is 180°.

Step2: Check other options

• \(m\angle5 + m\angle6 = m\angle1\): No basis.
• \(m\angle1 + m\angle2 = 180^\circ\): They are not supplementary.
• \(m\angle2 + m\angle3 = m\angle5\): Violates exterior angle theorem.

Answer:

B. \(m\angle3 + m\angle4 + m\angle5 = 180^\circ\)