4.9 write equations of parallel and perp. lines.notebook

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4.9 Write Equations of Parallel and Perpendicular Lines

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Parallel Lines

If two nonvertical lines in the same plane have the same slope, then they are parallel.

If two nonvertical lines in the same plane are parallel, then they have the same slope.

Converse statements:

Conditional statements: (if­then)

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4.9 write equations of parallel and perp. lines.notebook

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December 12, 2014

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Converse statements switch the hypothesis and the conclusion

example: If its rainy then its cloudy.

Hypothesis:

Conclusion:

Converse statement:

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Example 1) Write an equation of the line that passes through (­3, ­5) and is parallel to the line y=3x­1. now look at it

graphically...

4.9 write equations of parallel and perp. lines.notebook

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December 12, 2014

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Try it) Write an equation of the line that passes through (­2, 8) and is parallel to the line y=­2x+6.

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Perpendicular Lines intersect to form

Compare the slopes of the lines.

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Perpendicular Lines

If two nonvertical lines in the same plane have slopes that are negative reciprocals, then they are perpendicular.

If two nonvertical lines in the same plane are perpendicular then the lines have slopes that are negative reciprocals.

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Example

What is the slope of the given line?

What is the slope of a line perpendicular to the given line?

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Example 2) Write an equation of the line that passes through (1, ­4) and is perpendicular to the line

4.9 write equations of parallel and perp. lines.notebook

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December 12, 2014

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Try it) Write an equation of the line that passes through (­3, 8) and is perpendicular to the line

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4.9 write equations of parallel and perp. lines.notebook

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December 12, 2014

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