Math 1 · Unit 4 · Lesson 3 · part 1 of 5
The Words We Use
The vocabulary for this lesson, in one place.
Words we use
| Word | Plain English | What you do |
|---|---|---|
| Same line | Equal slope and equal y-intercept: one line written twice. | When slopes match, check b before saying parallel. |
| Parallel | Equal slopes, different y-intercepts. Never cross. | Same m, different b. |
| Perpendicular | Cross at a right angle. Slopes are negative reciprocals, product −1. | Multiply the slopes and look for −1. |
| Neither | Different slopes that do not multiply to −1. The lines cross, but not squarely. | Everything that is not the other three. |
| Slope (m) | Rise over run, the steepness and direction. | The one number that decides all four cases. |
| Negative reciprocal | Flip the fraction and change the sign. | The perpendicular slope. |