2. Let DÉ be a line passing through B, parallel to AC,
with angles as labeled.
defining a parallel line and labeling angles
3.
4. mZ1 = m24, and
m23= m 25.
Congruent angles have equal measures.
5.m24+ m22+ m25 = 180° angle addition and definition of a straight angle
6. m2 1 + m2 2 + m23 = 180° substitution
What is the missing step in this proof?
OA. Statement: 24 25, and 21 23.
Reason: Alternate Interior Angles Theorem
ОВ.
Statement: DÈ Is parallel to AC
Reason: AB is a transversal cutting De and AC-
OC Statement: 21 % 24, and 23 – 25.
Reason: Alternate Interior Angles Theorem
OD
Statement: 21 % 24, and 23 - 25.
Reason: 21 and 24, and 23 and 25 are pairs of supplementary angles.