Spherical Geometry Equilateral Pentagon

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SUMMARY

An equilateral pentagon cannot have four right angles in spherical geometry due to the properties of Lambert quadrilaterals. In spherical geometry, the sum of the angles in a polygon exceeds the Euclidean limit, requiring that each angle in a pentagon be greater than 108 degrees. Consequently, it is impossible to have four angles of 90 degrees in such a configuration, as this would violate the fundamental principles of spherical geometry.

PREREQUISITES
  • Spherical geometry fundamentals
  • Understanding of Lambert quadrilaterals
  • Knowledge of polygon angle sum properties
  • Familiarity with equilateral polygon characteristics
NEXT STEPS
  • Study the properties of Lambert quadrilaterals in depth
  • Explore the concept of angle sums in spherical polygons
  • Investigate the characteristics of equilateral polygons in non-Euclidean geometry
  • Learn about the applications of spherical geometry in various fields
USEFUL FOR

Mathematicians, geometry enthusiasts, educators, and students studying non-Euclidean geometry or spherical geometry concepts.

GeometryIsHARD
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Hey PF! I'm going through a textbook right now and it just said "obviously, you can't have an equilateral pentagon with 4 right angles in spherical geometry (Lambert quadrilaterals).

However, I am not able to make the connection. can somebody help me understand why this is?
 
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So every angle must be greater than 108 degrees and therefore it's quite obvious you can't have four of them being 90 degree's. Is that what you are saying?
 
GeometryIsHARD said:
So every angle must be greater than 108 degrees and therefore it's quite obvious you can't have four of them being 90 degree's. Is that what you are saying?

Yes.
 

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