Question

Consider the following statements about straight lines :
(1) Slope of horizontal line is zero and slope of vertical line is undefined.
(2) Two lines are parallel if and only if their slopes are equal.
(3) Two lines are perpendicular if and only if product of their slope is - 1.
Which of the above statements are true ?

• A. only (1)
• B. only (2)
• C. only (3)
• D. all the above

Answer 1

Answer: (D)

Correct answer is (d) all the above