CK-12 Geometry-Concepts

http://www.ck12.org Chapter 7. Similarity

10

15

=

BC

12

−→ 15 (BC) = 120

BC= 8

Example C

IsDE||CB?

Use the Triangle Proportionality Converse. If the ratios are equal, then the lines are parallel.
6
18 =

1

3 and

8

24 =

1
3
Because the ratios are equal,DE||CB.

Watch this video for help with the Examples above.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52551

CK-12 Foundation: Chapter7TriangleProportionalityB

Vocabulary

A line segment that connects two midpoints of the sides of a triangle is called amidsegment. A midpoint is a point
that divides a segment into two equal pieces. Pairs of numbers areproportionalif they are in the same ratio.

Guided Practice

Use the diagram to answers questions 1-5.DB‖F E.