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Parallel Lines and Proportional Parts. Triangle Proportionality Theorem If a line parallel to one side of a triangle intersects the other two sides in different points, then it divides those sides proportionally. Converse of the Triangle Proportionality Theorem
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Parallel Lines and Proportional Parts Triangle Proportionality Theorem • If a line parallel to one side of a triangle intersects the other two sides in different points, then it divides those sides proportionally. Converse of the Triangle Proportionality Theorem • If a line intersects two sides of a triangle in different points and divides those sides proportionally, then it is parallel to the third side.
In and Find BY. B Example 4-1c Answer: 15.75
In andAZ = 32. Determine whether Explain. X Answer: No; the segments are not in proportion since Example 4-2c
Parallel Lines and Proportional Parts Midsegment of a triangle – A line segment that connects the midpoints of two of its sides. Triangle Midsegment Theorem • The segment that joins the midpoints of two sides of a triangle is parallel to the third side and its length is half the length of the third side.
Triangle UXY has vertices U(–3, 1), X(3, 3), and Y(5, –7). is a midsegment of Example 4-3h
a. Find the coordinates of W and Z. b. Verify that c. Verify that Answer: Since the slope of and the slope of Answer: Therefore, Example 4-3i Answer: W(0, 2), Z(1, –3)
Parallel Lines and Proportional Parts Corollaries 6.1 – If three or more parallel lines intersect two transversals, then they cut off the transversals proportionally. 6.2 – If three or more parallel lines cut off congruent segments on one transversal, then they cut off congruent segments on every transversal.
Example 4-4c In the figure, Davis, Broad, and Main Streets are all parallel. The figure shows the distances in city blocks that the streets are apart. Find x. Answer: 5
Example 4-5d Find a and b. Answer: a = 11; b = 1.5