Question 172485
perpendicular lines have slopes that are negative reciprocals of each other. So what is the slope of the line {{{x = -7}}}? That line is a vertical line. It's slope is undefined. However, you know that a horizontal line is perpendicular to a vertical one.

What is the slope of a horizontal line?   0

So you have a point (0,2) and a slope of 0
That means we are looking for a horizontal line that runs thru the point (0,2).
We already know that m = 0
{{{y = mx +  b}}}
{{{y = 0*x + b}}}
{{{2 = 0*0 + b}}}
{{{2 = b}}}
The general formula for that line is
{{{y = 0*x + 2}}}
{{{y = 2}}}


You can do a more general look this way:
*[invoke find_line_by_slope_and_point 0, 2, 0]