Explanation
Correct answer: B.
Choice B is correct. The figure shows transversal intersecting lines and , where the angles labeled and are two corresponding angles and the angles labeled and are two corresponding angles. When a transversal intersects two lines, the lines are parallel if and only if two corresponding angles are congruent. It’s given that . If , then the two corresponding angles labeled and are congruent, which is sufficient to prove that lines and are parallel.
Desmos solution:
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. The angle labeled forms a linear pair with the angle labeled , so , or , regardless of whether lines and are parallel.
Choice C
Choice C is incorrect. Substituting for in this equation yields , or . Since the angle labeled and the angle labeled are corresponding angles, if and aren’t equal, then lines and can’t be parallel.
Choice D
Choice D is incorrect. The relationship describes a linear pair at line , which is true regardless of whether lines and are parallel.