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Pearson Geometry Common Core, 2011

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Pearson Geometry Common Core, 2011 View details

8. Slopes of Parallel and Perpendicular Lines

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Exercise 43 Page 203

If two lines are parallel they have the same slope and different y-intercepts. Two lines that are perpendicular have slopes whose product equals - 1.

Neither

Practice makes perfect

To enter the points into lists push STAT, choose Edit, and then enter the x-coordinates in L1 and the y-coordinates in L2.

To do a linear regression we push STAT, scroll right to CALC, and then choose the fourth option in the list, LinReg.

The slope of the line is - 0.125, and the y-intercepts is 1.625. With this information we can write the equation of the line.

y=- 0.125x+1.625 Let's change the lists in our calculator to the second set of points. Push STAT, choose Edit, and then enter the x-coordinates in L1 and the y-coordinates in L2.

Push STAT, scroll right to CALC, and then choose the fourth option in the list, LinReg.

The slope of the line is - 0.6, and the y-intercept is 3.2. With this information we can write the equation of the line. y=- 0.6x+3.2 Since the two lines have different slopes, we know they will intersect. If the lines are perpendicular the product of their slopes will equal - 1.

m_1m_2=- 1

m_1= - 0.125, m_2= - 0.6

( - 0.125)( - 0.6)? =- 1

Multiply

0.075≠ - 1

Since the product of the slopes does not equal - 1, we know that the lines are neither parallel or perpendicular.

Subchapter links

Lesson Check p.201

Practice and Problem-Solving Exercises p.201-204

Standardized Test Prep p.204

Mixed Review p.204