Question

which of the following statements are true? select all that apply. a. horizontal lines are always perpendicular to vertical lines. b. two lines which are not perpendicular to each other can never intersect. c. two distinct vertical lines are parallel. d. a line with a positive slope could be parallel to a line with a negative slope.

Explanation:

• A: By definition, horizontal lines (slope = 0) and vertical lines (undefined slope) are perpendicular.
• B: Non - perpendicular lines can intersect at non - 90 degree angles.
• C: Vertical lines have an undefined slope. All vertical lines have the same slope, so distinct vertical lines are parallel.
• D: Parallel lines have the same slope. A positive - slope line and a negative - slope line cannot have the same slope.

Answer:

A. Horizontal lines are always perpendicular to vertical lines.
C. Two distinct vertical lines are parallel.