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Slope – Parallel and Perpendicular Lines. Mrs. King and Ms. Reed Geometry Unit 12, Day 9. http://jwelker.lps.org/lessons/ppt/geod_3_3_slope.ppt. Slope - Defined. Given two points (x 1 , y 1 ) and (x 2 , y 2 ), the slope m of a line is defined to be:. Slope – Example #1.
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Slope – Parallel and Perpendicular Lines Mrs. King and Ms. Reed Geometry Unit 12, Day 9 http://jwelker.lps.org/lessons/ppt/geod_3_3_slope.ppt
Slope - Defined Given two points (x1, y1) and (x2, y2), the slope m of a line is defined to be:
Slope – Example #1 Given two points A(-3, -4) and B(3, 5), find the slope of the line through the points. Solution: Reduce fractions whenever possible.
Slope – Example #2a Find the slope of the line AB. A(-4, 4) B(1, 7) The slope of the line through AB is 3/5.
Slope – Example #2c On your own: Find the slope of EF. The slope of EF is -2/3. Since the slope is negative, the line runs down as we look from left to right. Positive slope runs up from left to right.
Slope – Example #2d On your own: Find the slope of CF. C(3,7) F(3, -6) Since division by zero is not defined, the slope of CF is undefined.
Slope – Vertical Lines The slope of any vertical line is undefined.
Slope – Example #3 On your own: Find the slope of MN. M(-1, 2) N(3, 2) The slope of MN is 0. MN is said to have zero slope.
Slope – Horizontal Lines The slope of any horizontal line is zero.
Slope – Other Lines Find the slope of PQ, RS, and TU. What can be said about lines PQ and RS? The lines are parallel and have the same slope.
Slope – Parallel Lines Parallel lines have equal slopes.
Slope – Other Lines What can be said about lines PQ and TU? The lines are perpendicular and have slopes which multiply to -1.
Slope – Perpendicular Lines Perpendicular lines have slopes which: • multiply to -1 • are negative reciprocals of each other. Horizontal and vertical lines are perpendicular to each other.
Slope – Example #4 Points R(3, -2) and S(-1, 3) form a line. a) find the slope of RS. b) find the slope of a line perpendicular to RS. Since perpendicular lines have slopes which are negative reciprocals, the slope of the perpendicular line is 4/5.
Practice • Matching Game: Calculate the slope! • http://www.quia.com/mc/499415.html
Homework • Work Packet: Slope, Parallel and Perpendicular Lines