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Find Radius from Pentagon's Area

Find Radius from Pentagon's Area
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2016-02-28 13:40
PolygonAngleGeometric Construction
This example demonstrates how to calculate the radius of a regular pentagon given its area. Key mathematical concepts include the area formula for regular polygons and geometric construction. Using GeoGebra commands such as TextField, Circle, Point, Rotate, Angle, Polygon, Segment, the construction process of a regular pentagon is visually illustrated. Suitable for students at the middle school level and above to learn about the properties and area calculation of regular polygons.

GeoGebra Commands & Parameters

  1. Textfield(ar) → InputBox1
  2. Circle(O, r) → c
  3. Point(c) → A
  4. Rotate(A, 72°, O) → B
  5. Angle(A, O, B) → α
  6. Polygon(A, B, 5) → poly1, a, b, d, e, f, C, D, E
  7. Segment(O, A) → g
  8. Segment(O, B) → h
  9. Segment(O, C) → i
  10. Segment(O, D) → j
  11. Segment(O, E) → k