Concepts in Action: Equivalence between the trapezoid and T2

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Age

6-9.

Materials

  • From the triangular box: grey equilateral triangle
  • From the small hexagonal box: yellow equilateral, three green equilateral triangles

Preparation


Presentation

  1. Unite the three green triangles to form a trapezoid.
  2. Knowing that each of these small triangles is congruent to the red triangle having the value of 1/4 T1, we can say that the trapezoid has the value of 3/4 T1.
  3. The trapezoid can be superimposed on the grey equilateral triangle to show that 1/4 is lacking.
  4. We've already seen that the red obtuse-angled triangle was equivalent to the small red equilateral triangle having the value of 1/4 T1.
  5. So each green triangle would also be equivalent to a red obtuse-angled triangle.
  6. These obtuse-angled triangles were each 1/3 of T2; T2 is composed of three obtuse-angled triangles having the value of 1/4 T1.
  7. Therefore T2 is equal to 3/4 T1.
  8. Having the same value of 3/4 T1, the trapezoid and T2 are equivalent.

Control Of Error


Points Of Interest


Purpose


Variation


Links


Handouts/Attachments