CK-12 Geometry Concepts

7.9. Parallel Lines and Transversals http://www.ck12.org

Example B

Findb.

To solve, set up a proportion.

12

9. 6

=

b

24

288 = 9. 6 b

b= 30

Example C

Find the value ofxthat makes the lines parallel.

To solve, set up a proportion and solve forx.

5

8

=

3. 75

2 x− 4

−→ 5 ( 2 x− 4 ) = 8 ( 3. 75 )

10 x− 20 = 30

10 x= 50

x= 5

Watch this video for help with the Examples above.

MEDIA

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CK-12 Foundation: Chapter7ParallelLinesandTransversalsB

Concept Problem Revisited

To findxandy, you need to set up a proportion using parallel the parallel lines.

2640

x

=

1320

2380

=

1980

y

From this,x= 4760 f tandy= 3570 f t.

To finda,b,andc, use the Pythagorean Theorem.

26402 +a^2 = 47602

39602 +b^2 = 71402

59402 +c^2 = 107102