Here's a little review on graphing and finding equations of perpendicular lines.
Example: Find the equation of the line that passes through the point (2, 3) and is perpendicular to the line
y = 3x - 5.
The slope of the line perpendicular to y = 3x – 5 must multiply by 3 equal -1. We think of the slope of the first line as m1 and the slope of the second line as m2, therefore 3(m1) = -1, so m1= -1/3.
Now we know that m = – 1/3, x = 2 and y =3.
Use the formula y = mx + b
3 = (-1/3)(2) + b
3 = -2/3 + b
3 2/3 = b
The equation of the line perpendicular to y = 3x – 5 that passes through the point (2, 3) is y = (-1/3)x + 11/3.
Notice the graph of both lines below.