80 likes | 216 Views
Lesson 6-4. Parallel Lines and Proportional Parts. Objectives. Use proportional parts of triangle Divide a segment into parts. Vocabulary. Midsegment: a segment whose endpoints are the midpoints of two sides of the triangle. S. Answer:. Example 1.
E N D
Lesson 6-4 Parallel Lines and Proportional Parts
Objectives • Use proportional parts of triangle • Divide a segment into parts
Vocabulary • Midsegment: a segment whose endpoints are the midpoints of two sides of the triangle
S Answer: Example 1 In ∆RST, RT // VU, SV = 3, VR = 8, and UT = 12. Find SU. From the Triangle Proportionality Theorem, Multiply. Divide each side by 8. Simplify.
B Example 2 In ∆ABC, AC // XY, AX=4, XB=10.5 and CY=6. Find BY. Answer: 15.75
Since the sides have proportional length. Answer: since the segments have proportional lengths, Example 3 In ∆DEF, DH=18, HE=36, and 2DG = GF. Determine whether GH // FE. Explain. In order to show that we must show that
X Answer: No; the segments are not in proportion since Example 4 In ∆WXZ, XY=15, YZ=25, WA=18 and AZ=32. Determine whether WX // AY. Explain.
Summary & Homework • Summary: • A segment that intersects two sides of a triangle and is parallel to the third side divides the two intersected sides in proportion • If two lines divide two segments in proportion, then the lines are parallel • Homework: Page 312 (14-26)