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Quadrilaterals

The big picture

Every tile in the corridor now has a name.

Ten ideas about a four-sided shape
IdeaHow it goes
Four sidesStraight, closed, no side crossing another.
Corner totalCut along a diagonal inside the shape. Four angles total 360°.
DiagonalsA line to a non-neighbour corner. A quadrilateral has 2.
Five namesTrapezium, parallelogram, rectangle, rhombus, square — each a list.
ParallelogramSides match, angles match, next-door angles total 180°.
HalvingA parallelogram's diagonals cut each other in half.
Matching lengthsEqual diagonals plus a parallelogram means a rectangle.
Square crossingFour equal sides make the diagonals cross at 90°.
Several namesA square is also a rhombus, a rectangle, a parallelogram.
Building oneFour sides need a fifth measurement to fix one shape.

Part I, Chapter 4 of your textbook is Quadrilaterals. Read it next.

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This track

  1. 0 Start here
  2. 1 Four straight sides, joined up
  3. 2 The four angles come to 360°
  4. 3 A line to the corner across
  5. 4 Five names and what each one demands
  6. 5 What a parallelogram gives you
  7. 6 Checkpoint: sides, angles and the family
  8. 7 Diagonals that cut each other in half
  9. 8 A rectangle also has matching diagonals
  10. 9 A rhombus crosses at a right angle
  11. 10 One shape, several names
  12. 11 Building one from measurements
  13. 12 Checkpoint: diagonals, names and building
  14. 13 The big picture
  15. 14 Track quiz

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