Answer:
A.
Step-by-step explanation:
We are given that two lines PQ and RS are intersect at point T.
We have to find the fact which is used to prove that angle PTS is always equal to angle RTQ.
We know that linear angles are supplementary and sum is 180 degrees
Therefore,[tex]\angle QTS+\angle PTS=180^{\circ}[/tex]
[tex]\angle QTS+\angle RTQ=180^{\circ}[/tex]
From both equation we get
[tex]\angle QTS+\angle RTQ=\angle QTS+\angle PTS[/tex]
Cancel angle QTS on both sided the we get
[tex]\angle RTQ=\angle PTS[/tex]
Hence, option A is true.
Therefore, when two lines are intersect then opposite angles are equal.
