February 2, 2015
Transcript of February 2, 2015
Parallel lines have the same slopes so find the slope of the given line and the slope you want for a parallel line will be the same.
Perpendicular lines have negative reciprocal slopes. Take the slope of the given line, switch the numerator and denominator and change the sign for the slope of its perpendicular line.
3
1m
3
1m
3
1m
31
3m
Parallel & Perpendicular Lines:
EXAMPLE 2
Determine whether lines are parallel or perpendicular
Line a: y = 5x – 3
Line b: x + 5y = 2
Line c: –10y – 2x = 0
SOLUTION Find the slopes of the lines.
Line a: The equation is in slope-intercept form. The slope is 5. Write the equations for lines b and c in slope-intercept form.
EXAMPLE 2:
Line b:x + 5y = 2 5y = – x + 2
Line c: –10y – 2x = 0 –10y = 2x y = – x15
Determine whether lines are parallel or perpendicular
xy = 25
15 +–
Determine which lines, if any, are parallel or perpendicular.
Line a: 2x + 6y = –3
Line b: y = 3x – 8
Line c: –1.5y + 4.5x = 6
ANSWER
parallel: b and c; perpendicular: a and b, a and c