Hyperbolic Geometry (Rectangles)

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In hyperbolic geometry, the interior angle sum of any triangle is less than 180°, which implies that rectangles, defined by four right angles summing to 360°, cannot exist. The discussion suggests using a diagonal to divide a quadrilateral into two triangles to explore this impossibility further. By analyzing the angles formed, it becomes evident that the conditions for a rectangle cannot be satisfied in hyperbolic space. The hint provided encourages considering the properties of triangles to aid in the proof. Thus, the conclusion is that rectangles cannot exist in hyperbolic geometry due to the fundamental properties of angles.
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Homework Statement


  1. Recall that in hyperbolic geometry the interior angle sum for any triangle is less than 180◦. Using this fact prove that it is impossible to have a rectangle in hyperbolic geometry.

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The Attempt at a Solution


- I wanted to use the idea that rectangles are 4 right angles meaning they would add up to 360 to help with the proof. I am not sure if that is useful, or even how I would write that in a proof.
 
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Hi SportsLover:

Here is hint. Think about a four sided figure that you might want to test to see if it is a rectangle. Think about a diagonal line connecting two corners. You now have two triangles.

Hope this helps.

Regards,
Buzz
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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