Investigation: Parallel and perpendicular lines

On the same set of axes graph the lines

1.  y = 3x + 7

2.  y = 3x –7

3.  y = 3x

4. What can you say about the slope of parallel lines?

On the same set of axes graph the lines

5.  y = 3x + 7

6.  y = - (1/3)x + 7

7.  y = 5x +3

8.  y= -(1/5)x

9. How does the line y = 3x + 7 compare to the line y = -(1/3)x +7?

10. How does the line y = 5x + 3 compare to the line y = -(1/5)x?

11.  What can you say about the slope of lines that are perpendicular?

12.  Write the equation of a line parallel to y = 3x + 1.

13.  Write the equation of a line perpendicular to y = 3x + 1.

14.  Write the equation of a line parallel to y = 3x +1 with y-intercept (0,-7).

15.  Write the equation of a line perpendicular to y = 3x +1 with y-intercept (0,-7).

16.  Write the equation of a line parallel to y = 3x –2 passing through (0,0)

17.  Write the equation of a line perpendicular to y = 3x –2 passing through (0,0)

18.  Write the equation of a line parallel to y = 3x +1 and passing through the point (1.2)

19.  Write the equation of a line perpendicular to y = 3x +1 and passing through the point (1,2)

20.  Given y = 3x + 5; y = 3x –4 ; y = (-1/3)x; y = (-1/3)x –7

a)  Which pairs of lines are parallel ?

b)  Which pairs of lines are perpendicular?