The reasoning that may be used for finding the measure of m∠12, is the
same side interior angles theorem.
The correct options using the drop-down menu are;
The sum of ∠1, ∠7, and ∠8 is 180°
∠8 and ∠12 are the same side interior angles
The measure of ∠12 must be = 120°
Stuart is not correct
The complete question is given below:-
In the diagram, line x is parallel to line y,m21= 65°, and m27 = 55°. Stuart says that m212 = 60°. His reasoning is shown. Step 1: mZ8 = 60°, because m21+ m27 +m28 = 180º. Step 2:28 212, because 28 and 212 are corresponding angles. Step 3: So, mZ12 = 60° Use the drop-down menus to explain whether or not Stuart is correct.
The angle is defined as the span between two intersecting lines or surfaces at or close to the point where they meet.
Given parameters;
Line x ║ line y
m∠1 = 65°, m∠7 = 55°
m∠12 = 60°
Stuart states ∠12 = 60°
The reasoning is presented as follows;
Step 1: m∠8 = 60°, because m∠1 + m∠7 + m∠8 = 180°
Step 2: ∠8 ≅ ∠12, because ∠8 and ∠12 are corresponding angles
Step 3: So, m∠12 = 60°
Using the drop-down menu, we have;
The sum of ∠1, ∠7, and ∠8 is 180° (Sum of angles in the triangle)
∠8 and ∠12 are same side interior angles (by definition)
Same side interior angles are supplementary, therefore;
∠8 +∠12 = 180°
∠12 = 180° - ∠8
Which gives;
The measure of ∠12 must be 180° - ∠8 = 180° - 60° = 120°
The measure of ∠12 must be = 120°
Stuart is not correct
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