Question

What is the first step in proving that the sum of the measures of triangle XYZ is 180°?

Answer 1

Answer:

To prove that sum of the measures of triangle XYZ is 180°

Out of the four options given

A. Construct a bisector of angle Z

B. Construct a midpoint of segment YZ

C. Construct a line parallel to segment XZ

D. Construct a perpendicular bisector of segment XY

Option C Construct a line parallel to segment XZ  is correct.

Draw a line l passing through vertex Y parallel to XZ. As alternate angles becomes equal, and applying linear pair axiom on point Y and then By substitution you can prove sum of the measures of angles of triangle XYZ is 180°.