Question

PQ and RS are two lines that intersect at point T.



Which fact is used to prove that angle PTS is always equal to angle RTQ?

Answer 1

Sum of the measures of angles RTQ and QTS is 180˚.
Sum of the measures of angles PTR and QTS is 180˚.
Line segments PQ and RS do not have a fixed length.
Lines PQ and RS intersect at an angle greater than a right angle.

Answer 2

do you know what vertical angles are?

Answer 3

< QTR and <STP are vertical angles and are congruent by the Vertical Angles Theorem. Yet, that is not what is being asked here.

What is asked is a critical step in proving the theorem that vertical angles these angles are congruent, a step that might appear in the proof of the theorem that vertical angles are congruent.

>>Sum of the measures of angles RTQ and QTS is 180˚.