1. 2.4 – Parallel and Perpendicular Lines

2. Slope = measure of steepness of a particular line/graph of an equation
Recall…
Slope = measure of steepness of a particular line/graph of an equation
m = Rise/Run OR

3. We can also look at slopes of multiple lines
Parallel ( || ): two lines are considered parallel, if and only if, their rise and run are both the same amount
IE, m1 = m2
Never intersect

4. Example. Find an equation, in slope-intercept form, that is parallel to the line 3x + 2y = 3y – 7 and passes through (1,2).
How do we find the slope of the given line?

5. Perpendicular ( ): two lines are perpendicular, if and only if, they are opposite reciprocals OR m1(m2) = -1
If horizontal and vertical, slopes of undefined and zero must occur
Intersection is 900 angle

6. Example. Find an equation, in slope-intercept form, that is perpendicular to the line 3x + y = 7 and passes through the point (-2, 5).
How can we find the given slope?
Same? OR?

7. Example. Determine if the two lines 3x + y = 2 and x + 3y = 2 are perpendicular, parallel, or neither.

8. Example. A parallelogram is a quadrilateral formed by two pairs of opposite parallel sides. Determine if following points form a quadrilateral (vertices listed counter-clockwise).
{(-2,2), (-5,-2), (2, -3), (5,1)}

9. Assignment
Pg. 161
1-25 even, 33