 # 2.5 Writing Equation of a Line Part 2 September 21, 2012.

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2.5 Writing Equation of a Line Part 2 September 21, 2012

In a coordinate plane, 2 lines are parallel if and only if they have the same slope. Slopes of Parallel Lines

Write Equations of Parallel Lines – The given line has a slope of 2. Any line parallel to this line will also have a slope of 2. – Write an equation of the line that passes through and is parallel to the line. 5 = 2x2xy+ – () 4 1,1, – y = mx + b 4 =-2(-1) + b 4 = 2+ b -2 2 = b y = -2x + 2 Simplify Solve for b Substitute 4 for y, -1 for x and -2 for m

Another Example Find the equation of a line going through the point (3, -5) and parallel to Using the point-slope equation where the slope m = - 2 / 3 and the point is (3, -5) we get OR

Find the equation of the line going through the point (4,1) and parallel to (click mouse for answer) Find the equation of the line going through the point (-2,7) and parallel to (click mouse for answer) Checkpoint

In a coordinate plane, 2 lines are perpendicular if and only if their slopes are opposite reciprocal of each other (or their product is –1) Slopes of Perpendicular Lines

Find the equation of a line going through the point (3, -5) and perpendicular to The slope of the perpendicular line will be m = 3 / 2. Using the point-slope equation where the slope m = 3 / 2 and the point (3, -5) we get Equation of a line Perpendicular to another line

Find the equation of the line going through the point (-6, -5) and perpendicular to y = -x + 2. Find the equation of the line going through the point (-2,7) and perpendicular to Checkpoint 1 = xy+

Homework : 2.5 p.98 #37-42ALL, 44-50even

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