Answer:
(C)
Step-by-step explanation:
Given: The ΔABC.
To prove: the sum of interior angles measures of ΔABC is 180°.
Proof:
Statement Reason
1. Let points A, B and C form a triangle given
2. Let DE be a line passing Defining a parallel line and labeling angles
through B and parallel to AC
with angles as labelled.
3. ∠1≅∠4 and ∠3≅∠5 Alternate interior angles theorem
4. m∠1=m∠4 and m∠3=m∠5 Congruent angles have equal measures
5.m∠4+m∠2+m∠5=180° Angle addition and definition of straight line
6.m∠1+m∠2+m∠3=180° Substitution
Hence proved
hence, option C is correct
