Sunday, November 23, 2014

Two congruent plane figures: exercise 2

Catatan ke-8


Exercise
Consider the plane figures below! Show the couples of the congruent figures? Explain step by step the answer.



Answer:
  • First of all, I must to know the requirements for the congruence of two plane figures. That are:
    • The corresponding lengths are equal; and
    • The corresponding angles are similar.
  • Second, in every tip of the trapezoids, I give a letter. Then I will get trapezoid ABCD, trapezoid EFGH, and trapezoid WXYZ. 

  • Fourth, solution for the trapezoid ABCD and EFGH
    • The followings are the size of corresponding angles:
      • ABC corresponds with FGH, then ABC = FGH
      • BCD corresponds with EFG, then BCD = EFG = x
      • CDA corresponds with HEF, then CDA = HEF = y
      • DAB corresponds with GHE, then DAB = GHE
      • The corresponding angles have similar sizes. It's mean, one requirement is fulfilled.
    • The followings are the length of corresponding sides:
      • AB corresponds with GH, then AB = GH
      • BC corresponds with FG, then BC = FG
      • CD corresponds with EF, then CD = EF
      • DA corresponds with PQ, then DA = HE
      • I got that the length of the corresponding sides have similar sizes. Hence, one requirement is fulfilled. 

  • Fifth, solution for the trapezoid ABCD and IJKL
    • The followings are the size of corresponding angles:
      • ABC corresponds with JKL, then ABC = JKL
      • BCD  corresponds with IJK, then BCD = IJK = x
      • CDA corresponds with LIJ, thenCDA = LIJ = y
      • DAB corresponds with KLI, then DAB = KLI
      • The corresponding angles have similar sizes. It's mean, one requirement is fulfilled.
    • The followings are the length of corresponding sides:
      • AB corresponds with KL, but AB ≠ KL
      • BC corresponds with JK, but BC ≠ JK
      • CD corresponds with IJ, but CD ≠ IJ
      • DA corresponds with LI, but DA ≠ LI
      • The result, I got that the length of the corresponding sides are not similar. Hence, one requirement is not fulfilled. 

  • Sixth, solution for the trapezoid EFGH and IJKL
    • The followings are the size of corresponding angles:
      • EFG corresponds with IJK, then EFG = IJK = x
      • FGH corresponds with JKL, then FGH = JKL
      • GHE corresponds with KLI, then GHE = KLI
      • HEF corresponds with LIJ, then HEF = LIJ =  y
      • The corresponding angles have similar sizes. It's mean, one requirement is fulfilled.
    • The followings are the length of corresponding sides:
      • EF corresponds with IJ, but EF IJ
      • FG corresponds with JK, but FG ≠ JK
      • GH corresponds with KL, but GH KL
      • HE corresponds with LI, but HE LI
      • The length of the corresponding sides has different sizes. Hence, one requirement is not fulfilled. 

  • Based on the description above I can conclude as follow:
    • The trapezoid ABCD is congruent with the trapezoid EFGH, because two requirements for the congruence of two plane figures are fulfilled.
    • The trapezoid ABCD is not congruent with the trapezoid IJKL because one of requirement is not fulfilled, that is the corresponding sides is not in equal size (AB ≠ KL, BC≠ JK, CD ≠ IJ, and DA ≠ LI).
    • The trapezoid EFGH is not congruent with the trapezoid IJKL because one of requirement is not fulfilled, that is the corresponding sides is not in equal size (GH ≠ KL, FG ≠ JK, EF ≠ IJ, and HE ≠ LI).


Happy blogging!

Ibnu Kahfi

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