Mathematics

Problem

In the following proof, lines l and m are intersected by a transversal t. Step 1:

\angle 1

and

\angle 2

are corresponding angles with respect to l, m and t. Step 2:

\angle 1 = \angle 3

(given). Step 3:

\angle 3 = \angle 2

(by the vertical angle theorem). Step 4: ______ Which of the following statements correctly completes Step 4 and therefore proves that l \u2225 m? a)

\angle 1

and

\angle 2

are alternate interior angles, therefore

l \parallel m

. b)

\angle 1 + \angle 2 = 180^{\circ}

, therefore

l \parallel m

. c)

\angle 1 = \angle 2

, therefore

l \parallel m

. d)

\angle 1 = \angle 2

, therefore

l \perp m