Question

Examine the paragraph proof. Which theorem does it offer proof for?

Answer 1

The proof states that:

$\begin{gathered} \angle XVZ+\angle ZVY=180 \\ \angle WVY+\angle ZVY=180 \end{gathered}$

Subtract the two equations to conclude that:

$\begin{gathered} \angle XVZ-\angle WVY=0 \\ \angle XVZ=\angle WVY \end{gathered}$

Similarly it can be proved that:

$\angle XVW=\angle ZVY$

This proof is for the vertical angle theorem.

Option C is correct.