For two similar polygons, the ratio of their side lengths is 4 : 9. What is the ratio of their perimeters?
Options
A
9 : 4
B
16 : 81
C
4 : 9
D
81 : 16
Answer & Analysis
Answer
C
Analysis
Question Analysis
The task is to determine the ratio of the perimeters of two similar polygons given their side-length ratio (4:9). The key is applying the property that perimeter ratios of similar polygons equal their side-length ratios.
Key Concept Explanation
For similar polygons, if the ratio of corresponding side lengths is , the ratio of their perimeters is also . This is because perimeter is a linear measurement directly proportional to side lengths.
Step-by-Step Solution
1. Apply the similarity property:
Given the side-length ratio , the perimeter ratio is directly . No calculations are needed—this is a direct application of the similarity principle.
Common Mistakes
Confusing perimeter with area ratios: Forgetting that perimeter ratios are linear () while area ratios are squared (
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