Question

Janet is trying to prove that the sum of the measures of the interior angles of a triangle is 180°.

Which reason can she use to justify the statement in line 6?
A
Alternate interior angles of parallel lines are congruent

B
Corresponding angles of parallel lines are congruent

C
Exterior Angle Theorem

D
Symmetric Property

Answer 1

c. exterior angle theorm

Answer 2

Answer : The correct option is, (A) Alternate interior angles of parallel lines are congruent.

Step-by-step explanation :

Exterior angle theorem : It is defined as the angle formed when we extend the side of a triangle is equal to the sum of its non-adjacent angles.

In the given figure, ∠1 = ∠2 +∠C

Alternate interior angles : It states that when two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent.

In the given figure, ∠1 ≅ ∠A and ∠3 ≅ ∠C

Hence, the correct option is, (A)