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Geometry: For Enjoyment and Challenge 4.6 Slope. Mike Beamish. Introduction. When lines are drawn on a plane, their slant is referred to as the slope of the line. Slope is a number that represents the change in the “y” coordinates and dividing this by the change in the “x” coordinates.
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Geometry:For Enjoyment and Challenge4.6Slope Mike Beamish
Introduction • When lines are drawn on a plane, their slant is referred to as the slope of the line. • Slope is a number that represents the change in the “y” coordinates and dividing this by the change in the “x” coordinates.
Positive Slopes • Lines that slope up and to the right have a positive slope.
Negative Slopes • Lines that slope down to the right have negative slopes
Rules • Horizontal lines have zero slope
Rules • Vertical lines have NO slope.
Rules • To test if lines are parallel, make sure they have the same slope.
Rules • To test if lines are perpendicular, check to see if their slopes are negative reciprocals.
Example • Example: • Given the diagram with triangle ABC. Find the slope of the altitude to BC, Find the length of the median to BC and find the slope of AD if it is parallel to BC. • Slope of BC = 8/12 or 2/3 • Slope of AN (altitude) = -3/2 (negative reciprocal) • The coordinates of M are (11,9) so the Slope of AM = -6/8 or - 3/4 • The slope of AD // BC = 2/3 since it must be the same.
Works Cited • Milauskas, George, Robert Whipple, and Richard Rhoad. Geometry: for Enjoyment and Challenge. New ed. Boston: McDougal Littell, 1996. 198-202. • Wing, Joan. "Chapter 4-2000." Joan Wing Mathematics. 25 Aug. 2002. 29 May 2008 <http://teacherweb.ftl.pinecrest.edu/wi ngjoa/My%20Webs/Geometry/Chapter %204.htm>.