How Many Triangles? 3

Topics: Starter | Problem Solving | Shape

• B Unit, Texas
• Saturday, February 14, 2009
• "There are 39, not 37"
• Ryan Ames, Edmonton
• Thursday, February 19, 2009
• "I count 51
  Not double counting anything
  and remembering that a triangle is just that three angles in which all angles together equal 180 and there is a bunch in there that are not right angles... Would love to know the correct answer though."
• Ricardo Estopier-Ayala, Strake Jesuit College Prep, Houston, Texas
• Wednesday, March 18, 2009
• "The correct answer is 37 triangles:
  There are:
  12 single triangles
  12 triangles composed of 2 single triangles
  6 triangles composed of 3 single triangles
  6 triangles composed of 4 single triangles and
  1 triangle composed of 6 single triangles.
  
  - The triangles composed of 3 single triangles were the hardest to find, but u can use the giant(composed of 6 single triangles) triangle to find them; they are all contained in it.
  - The triangle composed of 4 single triangles are the same triangles as the ones composed of 3 single triangles, except for the fact that they have just added one triangle to the end.
  - I am unsure how to respond to the person who found 51 triangles other than to say that he/she might have confused the definition of a triangle: A plane geometric figure with three angles and three sides."
• Australia Class, Preston, Lancashire, England
• Tuesday, June 26, 2012
• "Our class found different ways and strategies to solve this puzzle. We found 37 triangles and we enjoyed it! Thank you."
• Mr Kavanagh's Fifth Class, Cork, Ireland
• Thursday, May 23, 2013
• "Most of the class got lower numbers than 37. The teacher found 27 and when we looked at the answer we realised that there were 37. Abbie got the closest with 30."

 

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