Page 27 - Math Course 2 (Book 2)

Congruent and Similar Solids

Softballs and baseballs are both used to play a Determine whether the pair of solids is similar,
game with a bat. A softball has a diameter of 3.8 congruent, or neither.
inches, while a baseball has a diameter of about
2.9 inches. Find the ratio of the surface areas of the A. similar
two balls. B. congruent
C. neither

3.8 in. 2.9 in.

If the scale factor is a:b, then the ratio of the
2
surface areas is a : b 2

2
surface area of the larger ball a Theorem
= 13.1
2
surface area of the smaller ball b
2
1.3 a ≈ 1.3 and
≈ b =1
2
1 Answer
1.7
≈ Simplify
1
Similar and Congruent Solids
The ratio of the surface areas
Answer Two sizes of balloons are being used for
is about 1.7 : 1
decorating at a party. When fully inflated, the
balloons are spheres. The first balloon has a
diameter of 18 inches while the second balloon has
Your Turn! a radius of 7 inches. Find the scale factor of the
two balloons.

Similar and Congruent Solids
A. 18:7
B. 9:7
Determine whether the pair of solids is similar, C. 9:3.5
congruent, or neither. D. 2:1

A. similar
B. congruent
C. neither

Answer Answer

19