Teacher Information

This section provides notes for teachers and answers to the questions in the student activities. 

Activity 1 ó Cabri Geometryô Tour

Objectives

This activity is designed to help students to become accustomed to the CABRI software. They will complete the following activities:

  • Create and label points. 
  • Clear the screen. 
  • Select and remove errors. 
  • Create two intersecting lines. 
  • Create an angle. 
  • Measure an angle. 
  • Alter an angle. 
  • Bisect an angle. 
  • Create parallel lines. 
  • Create perpendicular lines. 
  • Create a triangle. 
Vocabulary
     
    point
    plane
    angle
    vertex
    parallel line
    triangle    		 line
    intersection
    ray
    bisect
    perpendicular line

Activity 9 ó Properties of Parallelograms

Objectives

This activity is designed to help students discover the following theorems:

  • If a quadrilateral is a parallelogram, then its opposite sides are congruent. 
  • If a quadrilateral is a parallelogram, then its opposite angles are congruent. 
  • If a quadrilateral is a parallelogram, then its consecutive angles are supplementary. 
  • If a quadrilateral is a parallelogram, then its diagonals bisect each other. 
Vocabulary
     
    parallelogram
    parallel
    opposite angles
    congruent
    bisect
    supplementary    		 segment
    angle
    consecutive angles
    diagonal
    intersection
Prerequisites

Students must understand how to:

  • Construct and label a segment. 
  • Construct parallel lines. 
  • Measure and label sides. 
  • Measure and label angles. 
Answers
  1. Sides AD and BC are congruent. 
  2. Sides AB and CD are congruent. 
  3. The relationship does not change. 
  4. The result does not change. 
  5. If a quadrilateral is a parallelogram, then its opposite sides are congruent. 
  6. angleA and angleC are congruent. 
  7. angleB and angleD are congruent. 
  8. The relationship does not change. 
  9. The result does not change. 
  10. If a quadrilateral is a parallelogram, then its opposite angles are congruent. 
  11. angleA and angleB are supplementary. 
  12. angleB and angleC are supplementary. 
  13. Yes, the relationship is the same. 
  14. The result does not change. 
  15. If a quadrilateral is a parallelogram, then its consecutive angles are supplementary. 
  16. The diagonals bisect each other. 
  17. Yes, the relationship is the same. 
  18. The result does not change. 
  19. If a quadrilateral is a parallelogram, then its diagonals bisect each other. 
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Cabri-Geometre II is available in the UK from Chartwell-Yorke, 114, High Street, Belmont Village, Bolton, Lancashire, BL7 8AL, tel 01204 811001, 01204 811008, info@chartwellyorke.com, http://www.chartwellyorke.com