Question

Which of the following postulates is not true?

a) Two angles whose measures add up to 180º are supplementary.
b) The sum of the measures of the interior angles of a triangle is 360º.
c) If a=b and b=c, then a=c.
d) A midpoint divides a line segment into two congruent segments.

Answer 1

The incorrect postulate is that the sum of the interior angles of a triangle is 360º; the correct sum is 180º. Other statements regarding supplementary angles, transitive property, and midpoints are true.

Step-by-step explanation:

The statement that is not true is b) The sum of the measures of the interior angles of a triangle is 360º. The correct statement is that the sum of the measures of the interior angles of a triangle is 180º. The other postulates listed are true: a) Two angles whose measures add up to 180º are supplementary. c) If a=b and b=c, then a=c is known as the transitive property. d) A midpoint divides a line segment into two congruent segments is the definition of a midpoint.