Question

Line L passes through the points (1, 1) and (7, 8). What is the slope of a line that is perpendicular to line L?

Answer 1

When a line passes through the two points $(x_{1},y_{1}) and (x_{2},y_{2})$ , its slope is given by the formula $m= \frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

In this question, a line L passes through the points $(1,1) and (7,8)$

So, its slope is given by $m=\frac{8-1}{7-1}$

$m=\frac{7}{6}$

When two lines are perpendicular, then the product of their slopes is -1.

Since, the slope of the line L is $\frac{7}{6}$ , so the slope of the line which is perpendicular to the given line L is $\frac{-6}{7}$ as the product of $\frac{-6}{7} \times \frac{7}{6}=-1$.