Triangle A has sides of lengths 12, 16, and 18. Triangle B is similar to triangle A and has a side with a length of 16. What are the possible lengths of the other two sides of triangle B?

1 Answer
Jan 23, 2017

There are 3 possible sets of lengths for Triangle B.

Explanation:

For triangles to be similar, all sides of Triangle A are in the same proportions to the corresponding sides in Triangle B.

If we call the lengths of the sides of each triangle {A1, A2, and A3} and {B1, B2, and B3}, we can say:

A1B1=A2B2=A3B3

or

12B1=16B2=18B3

The given information says that one of the sides of Triangle B is 16 but we don't know which side. It could be the shortest side (B1), the longest side (B3), or the "middle" side (B2) so we must consider all possibilities

If B1=16

1216=34
34=16B2B2=21.333
34=18B3B3=24

{16, 21.333, 24} is one possibility for Triangle B

If B2=16

1616=1 This is a special case where Triangle B is exactly the same as Triangle A. The triangles are congruent.

{12, 16, 18} is one possibility for Triangle B.

If B3=16

1816=98
98=12B1B1=10.667
98=16B2B2=14.222

{10.667, 14.222, 16} is one possibility for Triangle B.