Question

Lines a and b are perpendicular, the slope of line a is given below. What is the slope of line b? (A) 3 (B) 3/4 (C) -2 (D) -5/2 (E) -1/2 (F) 2/5 (G) 1

Answer 1

A) `-1/3`

B) `-4/3`

C) `1/2`

D) `2/5`

E) `2`

F) `5/2`

G) `-1`

Explanation:

The slopes of 2 perpendicular lines are related in that:
`m_1 * m_2 = -1`

So, if you know one slope, `m_1`, then the other slope, `m_2`, is the negative reciprocal of `m_1`:
`m_2 = -1/m_1`

A) If `m_1 = 3`, then: `m_2 = -1/3`
B) If `m_1 = 3/4`, then: `m_2 = -4/3`
C) If `m_1 = -2`, then: `m_2 = 1/2`
D) If `m_1 = -5/2`, then: `m_2 = 2/5`
E) If `m_1 = -1/2`, then: `m_2 = 2`
F) If `m_1 = 2/5`, then: `m_2 = 5/2`
G) If `m_1 = 1`, then: `m_2 = -1`