8.6 proportion and similar triangles. theorem triangle proportionality theorem if a line is parallel...
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8.6 Proportion and Similar Triangles
Theorem
Triangle Proportionality Theorem
If a line is parallel to one side of a triangle and intersects the other two sides, then it divides the two sides proportionally.
EC
AE
DB
AD
Converse of the Triangle Proportionally Theorem
If a line divides two sides of a triangle proportionally, then the line is parallel to the remaining side.
BCDEEC
AE
DB
AD//
Theorem
If three parallel lines are intersected by two lines, then the lines are divided proportionally.
Theorem
If a ray bisects one angle of a triangle, then it divides the sides proportional with the sides they are touching.
Solve for x
Solve for x
xxx
36)9(296
2
Show that DE // BC
975.9
2426
Show that DE // BC
975.9
2426
BCDEEC
AE
DB
AD//
Solve for x
96
8x
Solve for x
96
8x
x
x
x
3
15
948
89
6
Solve for x
2015
17
x
Solve for x
2015
17
x
7
27
25535
1525520
171520
20
17
15
x
x
xx
xx
xx
Homework
Page 502 – 503
# 11 - 28
Homework
Page 503 – 505
# 29 – 31,
34 – 37, 39,
41 – 50