Perpendicular lines
Compare the slopes of the perpendicular lines.
1. Move Point B to obtain a pair of perpendicular lines. Make sure B is on the intersection of a vertical and horizontal grid line.
2. Use the red slope triangle to write the slope of the red line in fraction form. Check your answer by changing the fraction to a decimal. Does your red slope match what is on the screen?
3. Use the blue slope triangle to write the slope of the blue line in fraction form. Check your answer by changing the fraction to a decimal. Does your blue slopes match what is on the screen?
4. Look at the fraction forms of the slopes for the blue and red line. What do you notice?
5. Repeat 1-3 for 3 new pairs of perpendicular lines.
6. Look at the measures of the angles where the two perpendicular lines intersect. What do you notice?