Question

If the slope of line p is 1/5 and the slope of line q is -5 then what is true about lines p and q? (assume lines p and q are coplanar)

a. they are parallel
b. they are perpendicular
c. they are neither parallel nor perpendicular
d. they are skew lines

Answer 1

B. They are perpendicular

Explanation:

They fit the criteria for what you need of a set of perpendicular lines.

Answer 2

For this case, we have to define perpendicular lines:

`m1 * m2 = -1`

We have then:

`m1 = \frac {1} {5}\\m2 = -5`

Then, according to the definition we have:

`(\frac {1} {5}) (- 5) = \frac {-5} {5} = -1`

We observe that the definition is fulfilled, therefore, the lines are perpendicular.

Answer:

b. they are perpendicular