Rise over run. Rise to your whY, run from your eX.
Key Idea: Slope
The slope measures the steepness of a line on a coordinate plane.
General Rule:
slope = rise / run = change in y / change in x“Rise” is the vertical change (change in ).
“Run” is the horizontal change (change in ).
Positive slope → line goes up; negative slope → line goes down.
Why this matters for the SAT:
Slope is used in algebra, linear equations, and coordinate geometry.
It helps quickly identify line steepness, compare lines, and solve for equations of lines.
Flip the fraction and sign of the slope.
Two lines are perpendicular if they intersect at a right angle (90°).
Their slopes are negative reciprocals of each other.
If one line has slope mm, the perpendicular line’s slope is:
Perpendicular slopes are used in coordinate geometry problems involving right angles, tangents to circles, and equation of a line questions. Remembering to flip the fraction and change the sign ensures accuracy.
