Similar Triangles Analysis: Finding Similarity Ratio Among Three Given Triangles

Triangle Similarity with Side Ratio Analysis

In the figure below there is a pair of similar triangles and a triangle that is not similar to the others.

Determine which are similar and calculate their similarity ratio.

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

In the figure below there is a pair of similar triangles and a triangle that is not similar to the others.

Determine which are similar and calculate their similarity ratio.

6663334.54.54.54442223336664443.53.53.5AAABBBCCCGGGHHHIIIDDDEEEFFFABC

2

Step-by-step solution

To solve the problem, we proceed with the following steps:

  • Identify the given side lengths for each triangle.
  • Compare the side ratios of each triangle pair to check for similarity.
  • Verify the side ratios to affirm the similarity ratio.
  • Select the correct multiple-choice answer based on the analysis.

Given side lengths:
Triangle C: 6 6 , 3 3 , 3 3 (perpendicular and base, as seen in figure).
Triangle B: 4.5 4.5 , 3 3 , 2 2 (perpendicular and base, as seen in figure).
Triangle A: 6 6 , 4 4 , 3.5 3.5 (perpendicular and base, as seen in figure).

Calculating the ratios:

  • For triangles C and B:
    64.5=32\frac{6}{4.5} = \frac{3}{2} which simplifies to 32=1.5\frac{3}{2} = 1.5, indicating that triangles C and B are similar.
  • Comparison for other pairs: Triangle A with Triangle B or C reveals no common proportionality.

Therefore, the only pair of similar triangles is C and B with a similarity ratio of 32\frac{3}{2} or 1.5.

The correct choice is, therefore, C + B are similar with a ratio of 1.5.

3

Final Answer

C + B are similar with a ratio of 1.5.

Key Points to Remember

Essential concepts to master this topic
  • Similarity Test: Compare all three pairs of corresponding sides between triangles
  • Ratio Method: Calculate 64=1.5 \frac{6}{4} = 1.5 and 32=1.5 \frac{3}{2} = 1.5 for matching proportions
  • Verification: All corresponding sides must have identical ratios: 1.5 = 1.5 = 1.5 ✓

Common Mistakes

Avoid these frequent errors
  • Comparing only two sides instead of all three corresponding sides
    Don't just check if two sides have the same ratio = incomplete similarity test! Two matching ratios don't guarantee similarity if the third pair doesn't match. Always verify that all three corresponding side pairs have identical ratios.

Practice Quiz

Test your knowledge with interactive questions

Is the similarity ratio between the three triangles equal to one?

FAQ

Everything you need to know about this question

How do I know which sides correspond to each other?

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Look at triangle orientation and position! In this problem, all triangles have the same shape and position. Match the longest side to longest side, shortest to shortest, and middle to middle.

What if I get different ratios for the same triangle pair?

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Then those triangles are NOT similar! Similar triangles must have all corresponding sides in the same ratio. Even one different ratio means they're not similar.

Can triangles be similar with a ratio less than 1?

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Absolutely! A ratio like 23=0.67 \frac{2}{3} = 0.67 just means the first triangle is smaller than the second. Ratios can be any positive number.

Why is the similarity ratio 1.5 and not 1.5:1?

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Both are correct ways to express it! 1.5 means the first triangle's sides are 1.5 times longer than the second triangle's sides. The ratio 1.5:1 means the same thing.

Do I need to check angles too?

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Not for this problem! When all three corresponding sides are proportional, the triangles are automatically similar. This is called SSS Similarity (Side-Side-Side).

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