To find b, we can pick our point (4,0), and plug the x and y coordinates into
the formula to solve for b:
To check, let’s take a look at our graph. Does it look like line r crosses the y-
axis at 6? It does indeed.
If two lines are perpendicular, then their slopes are the negative reciprocals
of each other. That mathy term negative reciprocal just means “flip the fraction
and negativize it.”
Is this a word? Yes.
—Samantha
What is the slope of a line perpendicular to the line ?
If the slope of the original line is , then the slope of the perpendicular
line is .
The SAT can also ask about the midpoint and distance between two points.
There is a formula for distance, and we will tell you that formula, but it is far
easier to draw a right triangle. Like in this problem:
What is the distance between points A and B?