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Warm Up for 9.6. Find the distance and midpointbetween the following sets of points. (5, 19) and (-3, -1) (7, -16) and (-2, -1) (1, -4) and (0, 0) (-6, 4) and (5, 20). Answers: distance. Answers: midpoint (1,9) (5/2, -15/2) (-1/2, -2) (-1/2, 12). Slope: algebra review #4.
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Warm Up for 9.6 Find the distance and midpointbetween the following sets of points. • (5, 19) and (-3, -1) • (7, -16) and (-2, -1) • (1, -4) and (0, 0) • (-6, 4) and (5, 20) Answers: distance • Answers: midpoint • (1,9) • (5/2, -15/2) • (-1/2, -2) • (-1/2, 12)
Slope:algebra review #4 What is slope? What is the slope formula? Slope = The steepness of a line.
Example 1 and 2: Find the slope between the two points. a. ( 7,6) and (3,1) Plug the numbers into the slope formula andsimplify b. ( -3, -15) and ( -5, 1) Plug the numbers into the slope formula andsimplify Watch out for DOUBLE NEGATIVES!
Last two examples: Example 3: find the slope of (7, 8) and (7, 5) undefined Plot the points and connect. “SLICES” through the x-axis at 7 • You can not have zero in the denominator so if you do the answer is “undefined” x=7 • The graph of a line with a undefined slope will be a vertical line. x y
Example 4: Find the slope of (5,9) and (-3,9) Plot the points and connect. “SLICES” through the y-axis at 9 • When zero is in the numerator the answer is just zero. y=9 x • The graph of a line with zero slope is a horizontal line y
Parallel and Perpendicular Lines • Lines that are parallel have _____________________________. • Lines that are perpendicular have ____________________________. the same slope opposite reciprocal slopes This means opposite signs and the fractions are flipped.
Discovering Parallel Lines • Predict which of the following will be parallel. • y = ½x + 1 • y = -3x – 4 • y = ½x – 4 • y = -½x + 1 1 and 2 since the slopes are the same.
Discovering Perpendicular Lines • Predict which lines will be perpendicular, explain your reasoning. • y = 4x + 1 • y = -4x + 1 • y = ¼x – 3 • y = x – 1 2 and 3 since one slope is negative, the other is positive and they are reciprocals of each other.
WRAP UP Find the slope and perpendicular slopes between the following sets of points. • (5, 19) and (-3, -1) • (7, -16) and (-2, -1) • (1, -4) and (0, 0) • (-6, 4) and (5, 20) Answers: The parallel slopes are the same. The perpendicular slopes are…. Negative Reciprocals! Opposite sign and flip!!!
Summary: • EXPLAIN WHAT IS THE SLOPE OF A LINE: FORMULA, HORIZONTAL LINE, VERTICAL LINE • EXPLAIN HOW TO FIND THE SLOPE OF ANOTHER LINE THAT IS PARALLEL TO AN EXISTING LINE. • EXPLAIN HOW TO FIND THE SLOPE OF ANOTHER LINE THAT IS PERPENDICULAR TO AN EXISTING LINE. Homework: Slope review worksheet