1. Parallel and perpendicular lines
2/20/18

2. 𝟓−𝟏 𝟒−𝟐 = 𝟒 𝟐 =𝟐
−𝟓−𝟎 𝟑−−𝟏 = −𝟓 𝟒
𝟏−𝟏 −𝟑−𝟐 = 𝟎 −𝟓 =𝟎
−5−2 −1−−1 = −7 0 =𝑢𝑛𝑑𝑒𝑓𝑖𝑛𝑒𝑑

3. WHAT DOES OPPOSITE RECIPROCAL MEAN???
If two lines are parallel, they have slopes that are THE SAME
If two lines are perpendicular, they have slopes that are OPPOSITE RECIPROCALS.
WHAT DOES OPPOSITE RECIPROCAL MEAN???
EXAMPLE: − 𝟐 𝟑 AND 𝟑 𝟐

4. Try these questions about parallel lines!

5. Same slopes! Equation must have SLOPE = 1/6 Equation must have
1. SLOPE = SLOPE = -2/3
3. SLOPE = SLOPE = -10/3
Same slopes!
Equation must have SLOPE = 1/6
Y-intercept must not be -3.5
Equation must have
SLOPE = 2
Y-intercept must not be 8
Equation must have
SLOPE = -3/2
Y-intercept must not be -2

6. Try these questions about perpendicular lines!

7. Opposite reciprocal slopes!
Perpendicular SLOPE = 5
SLOPE = -3/2
Perpendicular SLOPE = 2/3
Opposite reciprocal slopes!
Equation must have
SLOPE = -6
Equation must have
SLOPE = 2/3
Equation must have
SLOPE = -1/2

8. Hopefully you didn’t forget about point-slope form!!
𝒚=𝒎 𝒙− 𝒙 𝟏 + 𝒚 𝟏
Same slope
𝑦=3 𝑥−4 +7
𝑦=3𝑥−12+7
𝒚=𝟑𝒙−𝟓
Opposite reciprocal slope
𝑦=− 1 3 𝑥−4 +7

9. Same slope
𝑦=1 𝑥+2 +3
𝑦=𝑥+2+3
𝒚=𝒙+𝟓
Opposite reciprocal slope
𝑦=−1 𝑥+2 +3
Opposite reciprocal slope
𝑦=−2 𝑥−4 −5
𝑦=−2𝑥+8−5
𝒚=−𝟐𝒙+𝟑
Same slope
𝑦= 1 2 𝑥−4 −5

10. Complete the table…

11. (0, 2) (0, 1) (0, 1) (0, −13)
/7 −1/2 −9
−1/4 −7/ /9