Geometric Twins | FIO

Question 6

Suppose ΔHEN\Delta\text{HEN} is congruent to ΔBIG\Delta\text{BIG}. List all the other correct ways of expressing this congruence.

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Solution

When two triangles are congruent, their corresponding corners and sides are exactly the same.

Step 1 — Identify Corresponding Vertices

We are told that ΔHEN\Delta\text{HEN} is congruent to ΔBIG\Delta\text{BIG}. This means the order of the letters tells us which corners match. The first letter of the first triangle matches the first letter of the second. The second letter matches the second. The third letter matches the third.

So, we have these matching pairs: H corresponds to B. E corresponds to I. N corresponds to G.

Diagram 1

Step 2 — List All Other Congruence Statements

We can write the letters of the first triangle in any order. For each order, we must write the letters of the second triangle in the matching order. We already have one way: ΔHENΔBIG\Delta\text{HEN} \cong \Delta\text{BIG}. Let us find the other five ways.

  1. Let us write the first triangle as ΔHNE\Delta\text{HNE}.

    • H matches B.
    • N matches G.
    • E matches I. So, ΔHNEΔBGI\Delta\text{HNE} \cong \Delta\text{BGI}.
  2. Let us write the first triangle as ΔEHN\Delta\text{EHN}.

    • E matches I.
    • H matches B.
    • N matches G. So, ΔEHNΔIBG\Delta\text{EHN} \cong \Delta\text{IBG}.
  3. Let us write the first triangle as ΔENH\Delta\text{ENH}.

    • E matches I.
    • N matches G.
    • H matches B. So, ΔENHΔIGB\Delta\text{ENH} \cong \Delta\text{IGB}.
  4. Let us write the first triangle as ΔNHE\Delta\text{NHE}.

    • N matches G.
    • H matches B.
    • E matches I. So, ΔNHEΔGBI\Delta\text{NHE} \cong \Delta\text{GBI}.
  5. Let us write the first triangle as ΔNEH\Delta\text{NEH}.

    • N matches G.
    • E matches I.
    • H matches B. So, ΔNEHΔGIB\Delta\text{NEH} \cong \Delta\text{GIB}.

Answer

(i) ΔHNEΔBGI\Delta\text{HNE} \cong \Delta\text{BGI} (ii) ΔEHNΔIBG\Delta\text{EHN} \cong \Delta\text{IBG} (iii) ΔENHΔIGB\Delta\text{ENH} \cong \Delta\text{IGB} (iv) ΔNHEΔGBI\Delta\text{NHE} \cong \Delta\text{GBI} (v) ΔNEHΔGIB\Delta\text{NEH} \cong \Delta\text{GIB}

More questions in FIO

Q1

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Q2

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Q3

What measurements would you take to create a figure congruent to a given:

(a) Circle

(b) Rectangle

Q4

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(b) Rectangles are congruent?

Q5

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Q6

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Q7

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Q8

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Q9

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Q10

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Q11

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Q12

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Q13

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Q14

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Q15

Each of the following cases contains certain measurements taken from two triangles. Identify the pairs in which the triangles are congruent to each other, with reason. Express the congruence whenever they are congruent.

(a) AB = DE, BC = EF, CA = DF

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(c) AB = DF, \angleB = \angleD = 90°, AC = FE

(d) \angleA = \angleD, \angleB = \angleE, AC = DF

(e) AB = DF, \angleB = \angleF, AC = DE

Q16

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[Hint: AD is a transversal for these two lines. Are there any equal alternate angles?]

Q17

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Give more examples of two triangles where one triangle is congruent to the other in two different ways, as in the case above. Can you give an example of two triangles where one is congruent to the other in six different ways?

Q18

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Q19

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