Question

triangle abo is shown below: given: △abc prove: all three angles of △abc add up to 180°. the flowchart with missing reason proves the measures of the interior angles of △abc total 180°: which reason can be used to fill in the numbered blank space? (2 points) associative property of addition triangle exterior angle theorem angle addition postulate commutative property of addition

Explanation:

The numbered blank corresponds to justifying that $m\angle EBC + m\angle CBA + m\angle DBA = m\angle EBD$. This step combines adjacent angles along a straight line into the measure of the straight angle, which is defined by the Angle Addition Postulate, as it describes adding adjacent angle measures to get the measure of the larger combined angle.

Answer:

Angle Addition Postulate