january 17, 2014

17

Today:No Warm-Up: Final Exam

Wed.Review Parallel/Perp.

LinesComplete 4-4Class Work:

Six Question Review of Coordinate Unit

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:

Practice Problems:

EXAMPLE 2 Determine whether lines are parallel or perpendicular

Determine which lines, if any, 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

+–

GUIDED PRACTICE for Example 2

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

Class Work:

4-4Problems 2,4,6,8,10,

change to perpendicular.Problems 1,3,5,7,9,11,12;

parallel &Six Question Review of

Coordinate Unit