AN UNUSUAL RECTANGULAR ENVELOPE
Maths Workshop: Maths in an envelope
 
1. AN UNUSUAL RECTANGULAR ENVELOPE.

In the following window there is a rectangular envelope. However, in this envelope the point where the vertices meet is not necessarily found in the centre of the rectangle.
Esta unidad interactiva requiere la máquina virtual de Java J2RE.

In this window move the control points around the outside of the envelope to change its size and the position of the point where the four vertices meet. 

  1. Can you visualise the shape of the piece of paper needed to make this envelope? 

  1. Move the 4 control points until you get an envelope which is 5 units wide and 4 units high, making sure the point where the vertices meet is not in the centre.

  2. Make a rectangular, paper envelope which measures 12 x 6 cm where the vertices meet at a point which is 2cm from the bottom side and 2 cm from the left-hand side of the envelope.

  3. Can you make an envelope from any quadrilateral?

  4. What do the quadrilaterals used to make envelopes all have in common?

  5. Can we make a rectangular envelope by folding any sheet of paper or rectangular piece of paper?
       
           
  Ángel Cabezudo Bueno
 
Spanish Ministry of Education. Year 2001
 
 

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