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Learn about finding the distance between a point and a line by drawing perpendiculars and identifying equidistant lines. Understand the concept of equidistant lines and the theorem stating that equidistant lines from a third line are parallel. Practice solving problems involving parallel lines and finding distances using the distance formula.
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B A Distance between a Point and a Line: The distance between a point and a line, is the length of the segment perpendicular to the line from the point. Shortest distance C
Which segment in the diagram represents the distance from Rto XY? • A • B • C • D ___ ___ ___ ___ RY RX MX RM
d d a b c Equidistant: same distance. Theorem: In a plane if two lines are equidistant from a third line, then the two lines are parallel to each other. If the distance between line a and b is d and distance between b and c is d then a and c are Parallel.
Use to find the equation of the line perpendicular to the original two equations. Use one of the y intercepts of the original equations. So the equation of the green line is
Use system of equations to determine where the green line intersects the top blue equation. =
Now you know that at x=1 the green graph crosses the graph on top, plug in x=1 into the equation of the green line. The intersection point is (1,0)
Now use the distance formula: Between points (0,-3) and (1,0).
Homework • Textbook pages 185 – 187, • problems 1, 4 – 7, 10 – 18 evens, • and 36 – 42 evens.