Examples with solutions for The Ratio of Similarity: Applying the formula

Exercise #1

AAABBBCCCMMMNNN36 What is the ratio between the sides of the triangles ΔABC and ΔMNA?

Video Solution

Step-by-Step Solution

From the data in the drawing, it seems that angle M is equal to angle B

Also, angle A is an angle shared by both triangles ABC and AMN

That is, triangles ABC and AMN are similar respectively according to the angle-angle theorem.

According to the letters, the sides that are equal to each other are:

ABAM=BCMN=ACAN \frac{AB}{AM}=\frac{BC}{MN}=\frac{AC}{AN}

Now we can calculate the ratio between the sides of the given triangles:

MN=3,BC=6 MN=3,BC=6 63=2 \frac{6}{3}=2

Answer

BCMN=2 \frac{BC}{MN}=2

Exercise #2

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

Step-by-Step Solution

To answer the question, we first need to understand what "similarity ratio" means.

In similar triangles, the ratio between the sides is constant.

In the statement, we do not have data on any of the sides.

However, a similarity ratio of 1 means that the sides are exactly the same size.

That is, the triangles are not only similar but also congruent.

In the drawing, you can clearly see that the triangles are of different sizes and, therefore, clearly the similarity ratio between them is not 1.

Answer

No

Exercise #3

Triangle EDB is similar to triangle ABC.

Choose the correct answer.

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Video Solution

Step-by-Step Solution

The key property of similar triangles is that the ratios of the lengths of their corresponding sides are equal. For triangles EDB and ABC:

  • Triangle EDB is similar to triangle ABC, meaning:
  • Corresponding sides are proportional: ABBE=BCDB=ACED \frac{AB}{BE} = \frac{BC}{DB} = \frac{AC}{ED}

Therefore, the correct relationship among the sides, using the concept of similar triangles, is:

BCDB=ABBE=ACED \frac{BC}{DB} = \frac{AB}{BE} = \frac{AC}{ED}

This matches choice 3.

Thus, the correct answer to the problem is BCDB=ABBE=ACED \frac{BC}{DB}=\frac{AB}{BE}=\frac{AC}{ED} .

Answer

BCDB=ABBE=ACED \frac{BC}{DB}=\frac{AB}{BE}=\frac{AC}{ED}

Exercise #4

Are the triangles below similar? If so, what is their ratio?AAABBBCCCKKKLLLTTT6912342

Video Solution

Step-by-Step Solution

To determine if the triangles ABC \triangle ABC and KLT \triangle KLT are similar, we apply the Side-Side-Side (SSS) similarity criterion. This requires that the ratios of corresponding sides are equal.

We are given the side lengths: BC=12 BC = 12 , AB=9 AB = 9 , CA=6 CA = 6 for ABC \triangle ABC , and LK=2 LK = 2 , KT=3 KT = 3 , LT=4 LT = 4 for KLT \triangle KLT .

First, find the ratio for each pair of corresponding sides:

  • Compare BC BC and LT LT : BCLT=124=3 \frac{BC}{LT} = \frac{12}{4} = 3
  • Compare CA CA and LK LK : CALK=62=3 \frac{CA}{LK} = \frac{6}{2} = 3
  • Compare AB AB and KT KT : ABKT=93=3 \frac{AB}{KT} = \frac{9}{3} = 3

Since BCLT=CALK=ABKT=3 \frac{BC}{LT} = \frac{CA}{LK} = \frac{AB}{KT} = 3 , all sides maintain a constant ratio. Hence, the triangles are similar.

The similarity ratio is 3 3 , indicating ABCKLT \triangle ABC \sim \triangle KLT with a ratio of 3:1.

The correct choice, as given in the options, is:

Yes, similarity ratio:
BCLT=CALK=ABKT \frac{BC}{LT}=\frac{CA}{LK}=\frac{AB}{KT}

Answer

Yes, similarity ratio:
BCLT=CALK=ABKT \frac{BC}{LT}=\frac{CA}{LK}=\frac{AB}{KT}

Exercise #5

Triangles ADE and ABC are congruent.

Choose the correct answer.

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Video Solution

Step-by-Step Solution

To find the correct proportionality relationship between the triangles ADE and ABC, we need to identify the corresponding sides:

  • In triangle ADE, the sides AD AD , AE AE , and DE DE correspond to triangle ABC’s sides AB AB , AC AC , and BC BC , respectively.

Because these triangles are congruent, the ratios of their corresponding sides are equal:

ADAB=AEAC=DEBC \frac{AD}{AB} = \frac{AE}{AC} = \frac{DE}{BC}

This relationship matches with choice 1:

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

Therefore, the correct answer is choice 1.

Answer

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

Exercise #6

121212888333222EEEDDDBBBAAACCC What is the ratio between the lengths of sides AB and DE in triangles ΔCDE and ΔABC?

Video Solution

Step-by-Step Solution

To solve the problem, we need to determine the ratio of lengths between sides ABAB and DEDE in triangles ABC\triangle ABC and CDE\triangle CDE, using their similarity.

Given:

  • Triangle ABC\triangle ABC and triangle CDE\triangle CDE are similar by AA criterion, having common angle CC and both right triangles.
  • The vertical height from BB to AA is 33, while the vertical height from DD to CC is 1212.
  • The horizontal length from AA to CC is 22, and from CC to EE is 88.

To find the similarity ratio, we can compare corresponding segments:

  • The vertical height ratio is BDDE=312=14 \frac{BD}{DE} = \frac{3}{12} = \frac{1}{4} .
  • The horizontal base ratio is ACCE=28=14 \frac{AC}{CE} = \frac{2}{8} = \frac{1}{4} .

Thus, the triangles are similar with a ratio of 14 \frac{1}{4} .

Since all corresponding dimensions of similar triangles are proportional by this ratio, it follows:

  • ABDE=14 \frac{AB}{DE} = \frac{1}{4} .

Therefore, the solution to the problem is: ABDE=14 \frac{AB}{DE} = \frac{1}{4} .

The correct answer choice is: 14 \frac{1}{4} .

Answer

14 \frac{1}{4}

Exercise #7

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 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.

Answer

C + B are similar with a ratio of 1.5.

Exercise #8

In these figures, there is a pair of similar triangles and a triangle that is not similar to the others.

Determine which are similar and calculate their their similarity ratio.

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Step-by-Step Solution

To solve this problem, we'll compare the side ratios of the given triangles to determine which pair are similar and find the similarity ratio.

  • Step 1: Identify the given triangle side lengths:
    Triangle A: Sides of length 88, 44, and 66.
    Triangle B: Sides of length 1010, 66, and 88.
    Triangle C: Sides of length 44, 22, and 33.
  • Step 2: Compare the ratios of corresponding sides between pairs of triangles.

Comparing Triangle A and Triangle B:

  • Ratio 810=0.8 \frac{8}{10} = 0.8 ; 460.67 \frac{4}{6} \approx 0.67 ; 68=0.75 \frac{6}{8} = 0.75

Here, the ratios are not equal; hence, triangles A and B are not similar.

Comparing Triangle A and Triangle C:

  • Ratio 84=2 \frac{8}{4} = 2 ; 42=2 \frac{4}{2} = 2 ; 63=2 \frac{6}{3} = 2

All ratios are equal, so triangles A and C are similar, with a similarity ratio of 2.

Comparing Triangle B and Triangle C:

  • Ratio 104=2.5 \frac{10}{4} = 2.5 ; 62=3 \frac{6}{2} = 3 ; 832.67 \frac{8}{3} \approx 2.67

The ratios are not equal, so triangles B and C are not similar.

Therefore, the similar triangles are Triangle A and Triangle C, with a similarity ratio of 2.

The correct answer is A + C are similar with a ratio of 2.

Answer

A + C are similar with a ratio of 2

Exercise #9

AAABBBCCCMMMOOONNNFFFGGGHHH1810218182266What is the similarity ratio between triangles ΔGHF and ΔABC?

Video Solution

Step-by-Step Solution

To solve this problem, we need to calculate the similarity ratio between ΔGHF \Delta GH F and ΔABC \Delta ABC . Since both triangles are equilateral:

  • The side length of ΔABC \Delta ABC is 18 18 , and the side length of ΔGHF \Delta GH F is 2 2 .
  • The similarity ratio side of ΔABCside of ΔGHF \frac{\text{side of } \Delta ABC}{\text{side of } \Delta GHF} is:
  • \item 182=9. \frac{18}{2} = 9.

Therefore, the similarity ratio between triangles ΔGHF \Delta GHF and ΔABC \Delta ABC is 9 9 . The correct choice is:

ABGF=ACFH=9 \frac{AB}{GF}=\frac{AC}{FH}=9 .

Answer

ABGF=ACFH=9 \frac{AB}{GF}=\frac{AC}{FH}=9

Exercise #10

Given the triangle DBC similar to triangle ABC

Choose the correct answer:

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Video Solution

Step-by-Step Solution

To solve this problem, we need to use the properties of similar triangles. It is given that triangles DBC and ABC are similar. When triangles are similar, it means that their corresponding sides are proportional.

For triangles DBC and ABC, considering the similarity, the corresponding sides should satisfy:

  • ABBD=ACCD=BCBC \frac{AB}{BD} = \frac{AC}{CD} = \frac{BC}{BC}

The ratio BCBC\frac{BC}{BC} simplifies to 1, which is a characteristic of the proportional relationship between the sides of similar triangles.

To solve for the correct choice, let's compare this with the options provided:

  • Option 1: ADAB=AEAD=BCBC\frac{AD}{AB} = \frac{AE}{AD} = \frac{BC}{BC} - This does not align because segments AD and AE aren't involved in the main similarity relation.
  • Option 2: ABBD=ACCD=BCBC\frac{AB}{BD} = \frac{AC}{CD} = \frac{BC}{BC} - This perfectly aligns with our derived relationship.
  • Option 3: ADDB=AEEC=BCBC\frac{AD}{DB} = \frac{AE}{EC} = \frac{BC}{BC} - This option has segments that are not directly part of the triangles ABC and DBC as described.
  • Option 4: ADAB=AEAC=BCBC\frac{AD}{AB} = \frac{AE}{AC} = \frac{BC}{BC} - Again, this involves segments not described in the initial triangle similarity.

Therefore, the correct correspondence that mathematically represents the similarity of the given triangles is found in Option 2.

Hence, the correct relation of similarity is: ABBD=ACCD=BCBC\frac{AB}{BD} = \frac{AC}{CD} = \frac{BC}{BC}.

Answer

ABBD=ACCD=BCBC \frac{AB}{BD}=\frac{AC}{CD}=\frac{BC}{BC}

Exercise #11

Triangles ADE and ABC are similar.

Choose the appropriate answer.

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Video Solution

Step-by-Step Solution

To solve this problem, we will use the properties of similar triangles. In similar triangles, the corresponding sides are proportional. This means if triangles ADE and ABC are similar, the ratios of these corresponding sides must be equal. We can set up the proportion by considering:

  • Side AD AD in triangle ADE corresponds to side AB AB in triangle ABC.
  • Side AE AE in triangle ADE corresponds to side AC AC in triangle ABC.
  • Side DE DE in triangle ADE corresponds to side BC BC in triangle ABC.

Therefore, based on this correspondence, the ratio of the sides should be:

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

To confirm, let's ensure we are interpreting the similarity correctly:

  • Triangle ADE is similar to triangle ABC, meaning their corresponding angles are equal, and sides track on a consistent ratio.

Thus, based on the properties of similar triangles, the correct answer corresponding to these proportion relationships is:

ADAB=AEAC=DEBC\frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

This corresponds to choice 4.

Answer

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

Exercise #12

In the image there are 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 Solution

Triangle a and triangle b are similar according to the S.S.S (side side side) theorem

And the relationship between the sides is identical:

GHDE=HIEF=GIDF \frac{GH}{DE}=\frac{HI}{EF}=\frac{GI}{DF}

96=31=62=3 \frac{9}{6}=\frac{3}{1}=\frac{6}{2}=3

That is, the ratio between them is 1:3.

Answer

a a and b b , similarity ratio of 3 3

Exercise #13

Triangles ADE and ABC are congruent.

Choose the correct answer.

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Video Solution

Step-by-Step Solution

Triangles ADE and ABC are given as congruent. When two triangles are congruent, their corresponding sides are equal in proportion. Therefore, we need to find the correct proportional relationship between the sides of these triangles.

Let's recall that for two congruent triangles, their corresponding sides are in equal ratios. Specifically, for triangles ADE and ABC, the sides AD, AE, and DE correspond to the sides AB, AC, and BC, respectively.

Thus, the correct proportional relationship between the corresponding sides of triangles ADE and ABC is:

  • ADAB \frac{AD}{AB} corresponding to the first set of sides.
  • AEAC \frac{AE}{AC} corresponding to the second set of sides.
  • DEBC \frac{DE}{BC} corresponding to the third set of sides.

Therefore, the choice that correctly represents the proportional relationship of the sides of triangles ADE and ABC is:

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

Answer

ADAB=AEAC=DEBC \frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}

Exercise #14

BC is parallel to DE.

Calculate AE.

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Video Solution

Step-by-Step Solution

Let's prove that triangles ADE and ABC are similar using:

Since DE is parallel to BC, angles ADE and ABC are equal (according to the law - between parallel lines, corresponding angles are equal)

Angle DAE and angle BAC are equal since it's the same angle

After we proved that the triangles are similar, let's write the given data from the drawing according to the following similarity ratio:

ADAB=DEBC=AEAC \frac{AD}{AB}=\frac{DE}{BC}=\frac{AE}{AC}

We know that - AB=AD+DB=6+4=10 AB=AD+DB=6+4=10

610=10154=AEAC \frac{6}{10}=\frac{10}{154}=\frac{AE}{AC}

Let's reduce the fractions:

35=23 \frac{3}{5}=\frac{2}{3}

This statement is incorrect, meaning the data in the drawing contradicts the fact that the triangles are similar. Therefore, the drawing is impossible.

Answer

Impossible as the shape in the figure cannot exist.

Exercise #15

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Choose the correct answer.

Video Solution

Step-by-Step Solution

This problem involves identifying the correct similarity ratio of triangles based on given line segments. We have triangle ACF \triangle ACF with line segments AC AC and CF CF , and triangle BDV \triangle BDV with line segments BD BD and DV DV , where corresponding side lengths of similar triangles should satisfy proportional relationships.

First, recognize that for similar triangles, the ratio of corresponding sides should be equal. If triangles ACF \triangle ACF and BDV \triangle BDV are similar, the segments would meet certain proportional criteria. The possible ratios could be formed by recognizing:

  • FVAC \frac{FV}{AC} should correspond to the smaller segment extending from a vertex to base or equivalent in the other triangle setup.
  • DVAB \frac{DV}{AB} matches up the vertex downward extension similar to FVAC \frac{FV}{AC} with a base side.
  • FDBC \frac{FD}{BC} must be the ratio of a cross-cutting or diagonal side ratio to maintain similarity from base to opposite corner.

Thus, the correct setup for these segments should reflect that:
FVAC=DVAB=FDBC \frac{FV}{AC} = \frac{DV}{AB} = \frac{FD}{BC}

By evaluating each choice given, the correct answer would align with this reasoning. Therefore, the correct choice is: FVAC=DVAB=FDBC \frac{FV}{AC} = \frac{DV}{AB} = \frac{FD}{BC} .

Answer

FVAC=DVAB=FDBC \frac{FV}{AC}=\frac{DV}{AB}=\frac{FD}{BC}

Exercise #16

999555AAABBBDDDCCC ABCD is a rectangle.

What is the ratio of similarity between the lengths of the sides of triangles ΔBCD and ΔABC?

Video Solution

Step-by-Step Solution

To find the ratio of similarity between triangles BCD \triangle BCD and ABC \triangle ABC , we start by noting the configuration of rectangle ABCD ABCD .

Since ABCD ABCD is a rectangle, ABC \angle ABC and BCD \angle BCD are right angles. Thus, triangles BCD \triangle BCD and ABC \triangle ABC are right triangles.

Both triangles share the same height (side length BC=5 BC = 5 ) and base (in triangle BCD, DC=9 \triangle BCD, \ DC = 9 and in triangle ABC, AB=9 \triangle ABC, \ AB = 9).

The important observation is that despite differing configurations, these triangles maintain a proportionate structure, both sharing the same dimensions in the rectangle. This can make both triangles similar.

Thus, the ratio of similarity between the sides of BCD \triangle BCD and ABC \triangle ABC is 1.

Therefore, the solution to the problem is 1.

Answer

1

Exercise #17

AAABBBCCCDDDEEEFFFJJJ2461.5 Choose the correct answer.

Video Solution

Step-by-Step Solution

To solve this problem, let's follow these steps:

  • Step 1: Identify similar triangles and related segments.
  • Step 2: Apply proportions based on geometric similarity principles.
  • Step 3: Compare with the given options.

Let's work through each step:

Step 1: From the geometry, consider triangles and line segments such as ADAD, AFAF, and ABAB. These segments often form part of similar triangles with known properties.

Step 2: Based on triangle similarity properties, the ratio for segments in similar figures should follow a coherent pattern like that of proportions described for viable geometric figures, namely: ADAF=AFAB \frac{AD}{AF} = \frac{AF}{AB} This indicates the relationship of subsegments generated by these points. Use triangle proportionality theorem or similar property for derivation.

Step 3: Match this with the answer selections provided. The choice: ADAF=AFAB \frac{AD}{AF} = \frac{AF}{AB} corresponds directly with option 3 among the provided choices.

Therefore, the correct answer is: ADAF=AFAB \frac{AD}{AF}=\frac{AF}{AB} .

Answer

ADAF=AFAB \frac{AD}{AF}=\frac{AF}{AB}

Exercise #18

AAABBBCCCDDDEEEFFFΔABCΔDEF ΔABC≅Δ\text{DEF}

The above triangles are equilateral.

Choose the correct answer:

Video Solution

Step-by-Step Solution

To solve this problem, let's go through the steps clearly:

  • Step 1: Since triangles ABC \triangle ABC and DEF \triangle DEF are equilateral, each side of these triangles is equal to the other sides of the same triangle.
  • Step 2: Moreover, given that ABCDEF \triangle ABC \cong \triangle DEF , these triangles are congruent, meaning that the corresponding sides and angles are equal. Therefore, side AB=DE AB = DE , BC=EF BC = EF , and CA=FD CA = FD .

Since every side of ABC \triangle ABC is equal to every corresponding side of DEF \triangle DEF , the ratio between any corresponding sides of these triangles is:

ABDE=BCEF=CAFD=1 \frac{AB}{DE} = \frac{BC}{EF} = \frac{CA}{FD} = 1

Therefore, all sides have a ratio of 1 1 , which means that the correct statement is that "The ratio between the sides is equal to 1."

Therefore, the correct choice is choice 4.

Hence, the solution to this problem is: The ratio between the sides is equal to 1.

Answer

The ratio between the sides is equal to 1.

Exercise #19

The similarity ratio between two similar triangles is 7, so that the area ratio is —— _{——}

Video Solution

Step-by-Step Solution

We square it. 7 squared is equal to 49.

Answer

49

Exercise #20

The triangle ABC is similar to the triangle DEF.

The ratio between the lengths of their sides is 9:8.

What is the ratio between the areas of the triangles?

Video Solution

Step-by-Step Solution

We multiply the ratio by 2

9:8=18:16 9:8=18:16

Raised to the power of 2:

92:82=81:64 9^2:8^2=81:64

Answer

81:64