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  #### Resources tagged with Spheres similar to When the Angles of a Triangle Don't Add up to 180 Degrees:
  
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  ##### Other tags that relate to When the Angles of a Triangle Don't Add up to 180 Degrees
  Geodesics. Non Euclidean Geometry. Mathematical reasoning & proof. Spheres. Games. Real world. Visualising. Maths Supporting SET. Surface and surface area. Working systematically.
  
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  Broad Topics > 3D Geometry, Shape and Space > Spheres
  
  ### When the Angles of a Triangle Don't Add up to 180 Degrees
  
  ##### Stage: 4 and 5
  
  This article outlines the underlying axioms of spherical geometry giving a simple proof that the sum of the angles of a triangle on the surface of a unit sphere is equal to pi plus the area of the. . . .
  
  ### There and Back Again
  
  ##### Stage: 3 Challenge Level:
  
  Bilbo goes on an adventure, before arriving back home. Using the information given about his journey, can you work out where Bilbo lives?
  
  ### Ball Packing
  
  ##### Stage: 4 Challenge Level:
  
  If a ball is rolled into the corner of a room how far is its centre from the corner?
  
  ### Three Balls
  
  ##### Stage: 4 Challenge Level:
  
  A circle has centre O and angle POR = angle QOR. Construct tangents at P and Q meeting at T. Draw a circle with diameter OT. Do P and Q lie inside, or on, or outside this circle?
  
  ### Mouhefanggai
  
  ##### Stage: 4
  
  Imagine two identical cylindrical pipes meeting at right angles and think about the shape of the space which belongs to both pipes. Early Chinese mathematicians call this shape the mouhefanggai.