Investigating the Properties of an Isosceles Trapezoid

Investigating the Properties of an Isosceles Trapezoid
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2017-08-12 02:30
This example demonstrates the properties of an isosceles trapezoid. Key mathematical concepts include linear equations, properties of isosceles trapezoids, and logical reasoning. Using GeoGebra commands such as Corner, Simplify, and If, the construction process of the isosceles trapezoid is dynamically displayed. Suitable for middle school and above students to learn geometric construction and logical reasoning.

GeoGebra Commands & Parameters

  1. LaTeX(steps) → counter
  2. LaTeX("\text{Move the slider to solve the problem.}") → text0
  3. LaTeX("\text{Use the buttons below to return to the original}\cr\text{problem or randomly generate a similar practice}\cr\text{problem.}") → RandomizationText
  4. Corner(2, 3) → topright
  5. Corner(2, 1) → bottomleft
  6. Simplify((ga * x) + gb) → g
  7. If(gb > 0, LaTeX[("+" * gb)], LaTeX[gb]) → gadd
  8. If(ydiff ≟ 0, LaTeX["satisfies"], LaTeX["approximately satisfies"]) → sat
  9. If(ydiff ≟ 0, LaTeX["x-coordinate"], LaTeX["approximate x-coordinate"]) → coord
  10. If(ydiff ≟ 0, LaTeX["solution"], LaTeX["approximate solution"]) → soln
  11. LaTeX((((("\text{Use a table of values to approximate the solution set}\cr\text{for the following system of equations.}\cr\text{Find }\textcolor{#000099}{f(x) – g(x)}\text{ for your estimates.}\cr\textcolor{#000099}{f(x)=" * f) * "}\cr\textcolor{#000099}{g(x)=") * g) * "}")) → Problem
  12. LaTeX((((("\text{Create a table of values for }\textcolor{#000099}{f(x) = " * f) * "}\text{ and }\cr\textcolor{#000099}{g(x) = ") * g) * "}\text{.}")) → text1
  13. Sequence(i, i, (-xscale), xscale) → xvalues
  14. Zip(f(j), j, xvalues) → fvalues
  15. Zip(g(j), j, xvalues) → gvalues
  16. Zip(j - k, j, fvalues, k, gvalues) → fgdiffs
  17. TableText({Append[LaTeX["\textcolor{#000099}{x}"], xvalues], Append[LaTeX["\textcolor{#000099}{f(x)}"], fvalues], Append[LaTeX["\textcolor{#000099}{g(x)}"], gvalues], Append[LaTeX["\textcolor{#000099}{f(x)-g(x)}"], fgdiffs]}, "vr") → text2
  18. LaTeX("\text{In column }\textcolor{#000099}{f(x) – g(x)}\text{, look for sign changes.}") → text3
  19. Sequence(If[sgn(fgdiffs(k)) ≟ sgn(fgdiffs(k + 1)), "F", "T"], k, 1, Length[fgdiffs] - 2) → signChange
  20. Length(signChange \ {"F"}) → numrows
  21. IndexOf("T", signChange) → firstchange
  22. LaTeX((((("\text{There is a sign change from }\textcolor{#000099}{x=" * xvalues(firstchange)) * "}\text{ to }\textcolor{#000099}{x=") * xvalues(firstchange + numrows)) * "}\text{.}")) → text4
  23. Sequence(fgdiffs(k), k, firstchange, firstchange + numrows) → fgdiffsS
  24. Sequence(fvalues(k), k, firstchange, firstchange + numrows) → fvaluesS
  25. Sequence(gvalues(k), k, firstchange, firstchange + numrows) → gvaluesS
  26. Sequence(xvalues(k), k, firstchange, firstchange + numrows) → xvaluesS
  27. TableText({Append[LaTeX["\textcolor{#000099}{x}"], xvaluesS], Append[LaTeX["\textcolor{#000099}{f(x)}"], fvaluesS], Append[LaTeX["\textcolor{#000099}{g(x)}"], gvaluesS], Append[LaTeX["\textcolor{#000099}{f(x)-g(x)}"], fgdiffsS]}, "vr") → text4b
  28. If(solx ≟ floor(solx), "int", "rat") → version
  29. LaTeX(LaTeX["\text{The sign change occurs between adjacent integers}\cr\text{so look at values in between them.}"]) → text5B
  30. Sequence(k, k, xvalues(firstchange), xvalues(firstchange) + 1, 0.1) → xvalues2
  31. Zip(f(k), k, xvalues2) → fvalues2
  32. Zip(g(k), k, xvalues2) → gvalues2
  33. Zip(j - k, j, fvalues2, k, gvalues2) → fgdiffs2
  34. Sequence(If[sgn(fgdiffs2(k)) ≟ sgn(fgdiffs2(k + 1)), "F", "T"], k, 1, Length[fgdiffs2] - 2) → signChange2
  35. LaTeX((((((("\text{Between these points, at }\textcolor{#000099}{x=" * solx) * "}\text{,}\cr\textcolor{#000099}{f(x)-g(x)=") * yapproxf) * "- (") * yapproxg) * ")= 0}\text{.}")) → text5
  36. LaTeX((((((((("\text{This tells us the curves }\textcolor{#000099}{f}\text{ and }\textcolor{#000099}{g}\text{ intersect at }\cr\textcolor{#000099}{x = " * xapprox) * "}\text{. The corresponding y-value is}\cr\text{}\textcolor{#000099}{") * yapproxf) * "}\text{. }\text{Therefore, the solution set of this}\cr\text{system is }\textcolor{#000099}{(") * xapprox) * ", ") * yapproxf) * ")}\text{.}")) → text6
  37. TableText({Append[LaTeX["\textcolor{#000099}{x}"], xvalues2], Append[LaTeX["\textcolor{#000099}{f(x)}"], fvalues2], Append[LaTeX["\textcolor{#000099}{g(x)}"], gvalues2], Append[LaTeX["\textcolor{#000099}{f(x)-g(x)}"], fgdiffs2]}, "vr") → text5C
  38. LaTeX((((((((("\text{This tells us the curves }\textcolor{#000099}{f}\text{ and }\textcolor{#000099}{g}\text{ intersect at }\cr\text{approximately }\textcolor{#000099}{x \approx " * solx) * "}\text{. The corresponding y-value}\cr\text{is approximately }\textcolor{#000099}{") * soly) * "}\text{. }\text{Therefore, the approximate}\cr\text{solution set of this system is }\textcolor{#000099}{(") * solx) * ", ") * soly) * ")}\text{.}")) → text6B
  39. Length(signChange2 \ {"F"}) → Sign2Count
  40. LaTeX("\text{Since zero once again doesn't show up in the }\cr\textcolor{#000099}{f(x)-g(x)}\text{ values, the actual intersection falls}\cr\text{between table values. The solution above rounds}\cr\text{to the nearest tenth.}") → text6C