# Parallel and perpendicular lines investigation using Geogebra

```MYP 9 Mathematics
Name: ____________________________
Investigate:
A.
Consider two lines:
L1: y = 3x – 4 and L2: y = 3x + 5
State the slope and y-intercept of each line.
……………………………………………..
……………………………………………..
Open Geogebra and graph the lines on the same set of axes.
Describe what you notice about the lines.
……………………………………………..
……………………………………………..
1
1
Try another:
L3: y = − 5x + 2 and L4: y = − 5x + 8
State the slope and y-intercept of each line.
……………………………………………..
……………………………………………..
……………………………………………..
……………………………………………..
Write a general statement about lines with the same slope.
………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………
Exercise:
State 3 lines which are parallel to:
1. y = 4x + 2
2. y = 2x + 2
3. y = x – 2
4. y = −3x + 5
Write the equation of the line parallel to y = 3x + 2 and passes through the point (0, 1).
MYP 9 Mathematics
Name: ____________________________
B.
Using Geogebra, graph these two lines on the same set of axes:
1
L1: y = 3x + 5 and L2: y = − 3x + 1
State the slope of each line. ……………………………………………..
Find the angle between the lines: ………………………………
Describe what you notice about the lines and their slopes.
……………………………………………..
……………………………………………..
Try another:
Graph these lines on the same set of axes.
2
3
L3: y = − 3x – 3 and L4: y = 2x – 8
State the slope of each line. ……………………………………………..
Find the angle between the lines: ………………………………
……………………………………………..
……………………………………………..
Write a general statement about perpendicular lines and their slopes.
………………………………………………………………………………………………………………………
………………………………………………………………………………………………………………………
Exercise:
State 3 lines which are perpendicular to:
1. y = 4x + 2
2. y = x + 2
3. y = –2x – 2
4. y = − 2x + 5
1
Write the equation of the line which is perpendicular to y = 3x + 2 and passes through the point
(0, 2).
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