Question

Put the steps up above in order.​

Answer 1

1. Given

2. Vertical Angles Theorem (1st Occurrence)

3. Vertical Angles Theorem (1st Occurrence)

4. Transitive Property of Congruence

5. Converse of the Alternate Interior Angles Theorem

Explanation:

Vertical Angles Theorem

When two straight lines intersect, the opposite vertical angles are congruent.

Transitive Property of Congruence

If one pair of angles is congruent to a third angle, then the first angle is congruent to the third angle.

Converse of the Alternate Interior Angles Theorem

If two lines are intersected by a transversal so that the alternate interior angles are congruent, then the lines are parallel.

`\begin{array}l\vphantom{\frac12} \sf Statements & \sf Reasons \\\cline{1-2}\\1. \; \angle 2 \cong \angle 7 & 1.\; \sf Given\\\\2. \; \angle 2 \cong \angle 3 & 2.\; \sf Vertical\;Angles\;Theorem\;(1st\;Occurrence)\\\\3. \; \angle 6 \cong \angle 7 & 3.\;\sf Vertical\;Angles\;Theorem\;(2nd\;Occurrence)\\\\4. \; \angle 3 \cong \angle 6 & 4.\;\sf Transitive\;Property\;of\;Congruence\\\\5. \; a \parallel b & 5.\;\sf Converse\;of\;the\;Alternate\;Interior\;Angles\;Theorem\\\\ \end{array}`

From inspection of the given diagram, we can see that angles 2 and 3 are vertical angles, similarly angles 6 and 7 are vertical angles. Therefore, the Vertical Angles Theorem applies.

According to the Transitive Property of Congruence, if ∠2 ≅ ∠7 and ∠2 ≅ ∠3 and ∠6 ≅ ∠7 then ∠3 ≅ ∠6.

The two lines a and b are intersected by transversal
`\ell` so that the alternative interior angles 3 and 6 area congruent, then the lines a and b are parallel. This is the Converse of the Alternate Interior Angles Theorem.