http://www.ck12.org Chapter 7. Similarity
Vocabulary
Pairs of numbers areproportionalif they are in the same ratio. Two lines areparallelif they have the same slope
and thus never intersect. Atransversalis a line intersecting a system of lines.
Guided Practice
Finda,b,andc.
Look at the corresponding segments. Only the segment marked “2” is opposite a number, all the other segments are
opposite variables. That means we will be using this ratio, 2:3 in all of our proportions.
a
2=
9
3
2
4
=
3
b2
3
=
3
c
3 a= 18 2 b= 12 2 c= 9
a= 6 b= 6 c= 4. 5There are several ratios you can use to solve this example. To solve forb, you could have used the proportion^64 =^9 b,
which will still give you the same answer.
Explore More
Find the value of each variable in the pictures below.