Make sure parallel line and parallel line slope are both checked above. Move the slope slider (m) back and forth. What do you notice about the slopes of the parallel lines?
Parallel lines have the same slope.
Parallel Lines and Y-Intercepts
Move the Y-intercept slider this time. What if the two lines have the same y-intercept? What do you notice? Can parallel lines have the same y-intercept?
If the y-intercepts are the same, they are the same line and are no longer parallel.
Perpendicular Slope Conjecture Investigation Q1
Uncheck the parallel boxes and check the perpendicular boxes. Type the slope of the pink line as a fraction in simplest form then type the slope of the green (perpendicular) line as a fraction in simplest form. Use the grid to help you. You may need to zoom in to see the grid better.
Answers may vary
Perpendicular Slope Conjecture Investigation Q2
Move the slope slider and type the slope of the pink line and the green line as fractions in simplest form. (No decimals)
answers will vary
Perpendicular Slope Conjecture Investigation Q3
Once more, move the slope slider and type the slope of the pink line and the green line as fractions in simplest form.
answers will vary.
Perpendicular Slope Conjecture
If two lines are perpendicular, then their slopes are _____________________ and ________________________.
opposite and reciprocals
Perpendicular Lines and Y-Intercepts
Move the y-intercept slider around. Can perpendicular lines have the same y-intercept?
Yes
Check for understanding #1
Suppose line l is parallel to line m, if the slope of line l is 4/5, what is the slope of line m?
4/5
Check for understanding #2
Suppose line l is perpendicular to line n, if the slope of line l is 2/3, what is the slope of line n?
-3/2
Check for understanding #3
Suppose line s is perpendicular to line t, if the slope of line s is -4, what is the slope of line t?
1/4
Extension
Suppose line y is perpendicular to line z, if the slope of line y is 0, what is the slope of line z? (What do the lines look like?)