Points A, B, and form a triangle. Complete the statements to prove that the sum of the interior angles of AABC is 180°. Reason
Statement
Points A, B, and C form a triangle.
Let DE be a line passing through Band parallel to AC
23 25 and 21 24
given
definition of parallel lines
v
m_1 = m 24 and m 3 = m25
v
m24+ m22 + m25 = 180°
angle addition and definition of a straight line
substitution
m21 + m22 + m23 = 180°
All