Precalculus, Chapter 1, 1.3, Section 1.3, Problem 70

Determine the equation of the line that is perpendicular to the line $y = 8$ containing the point $(3,4)$. Express your answer using the general form or the slope intercept form of the equation of a line, which ever you prefer.

The line $y = 8$ is a horizontal line and horizontal line is perpendicular to a vertical line. And the vertical line contains the point $(3,4)$. We know that the equation for a vertical line has a form $x = a$, where $a$ is the $x$-intercept. If point $(3,4)$ is on the line then the $x$-intercept is $(3,0)$. So the equation of the line is $x = 3$.