Comparing Logical Systems SOLUTION

Comparing Logical Systems SOLUTION

3.3 Deductive & Inductive Reasoning 127 Comparing Logical Systems There are many possible “non-Euclidean” geometries. One is called spherical geometry. The difference between Euclidean and spherical geometry lies in what you assume the undefi ned term line to be and also in the Parallel Postulate. Here is one set of postulates for spherical geometry. 1. A unique straight line can be drawn between any two points, unless the points are antipodal, in which case they lie on many straight lines. 2. Any straight line segment can be extended indefi nitely in a straight line. (At some point, it will connect with itself, but it can go around the sphere In spherical geometry, the an infi nite number of times.) undefi ned term line is imagined 3. A circle can be described with any given point as its center and any distance to be a great circle of a sphere. as its radius, as long as the radius is less than half the circumference of Longitude lines on Earth are great the sphere. circles. Latitude lines, except for the equator, are not great circles. 4. All right angles are equal. 5. Parallel Postulate: No two lines are parallel. (Any two intersect.) Explain why the Spherical Parallel Postulate makes sense. SOLUTION If you were to tell someone that “no two lines are parallel,” that person might think that you are irrational. What needs to be understood is that your understanding of terms is different. • In spherical geometry, you understand a “line” to be a great circle of a sphere. For you, a “plane” is the surface of the sphere. • In Euclidean geometry, you understand a “line” to be straight, like a laser beam. For you, a “plane” is a fl at surface. • You both understand that two lines are “parallel” if they lie in the same plane and don’t intersect. To see why there are no parallel lines in spherical geometry, imagine putting a rubber band around a tennis ball. Make it a great circle so that it has a maximum circumference. Now try to put a second rubber band (great circle) on the ball. You can’t do it without intersecting the fi rst rubber band. Checkpoint Help at In Euclidean geometry, you know that the sides of a triangle are three straight line segments. You also know that the 3 angle measures total 180°. Sketch and describe a triangle in spherical geometry. What can you say about the sum of the angle measures of a triangle in spherical geometry? Copyright © Larson Texts, Inc. All rights reserved..

View Full Text

Details

  • File Type
    pdf
  • Upload Time
    -
  • Content Languages
    English
  • Upload User
    Anonymous/Not logged-in
  • File Pages
    1 Page
  • File Size
    -

Download

Channel Download Status
Express Download Enable

Copyright

We respect the copyrights and intellectual property rights of all users. All uploaded documents are either original works of the uploader or authorized works of the rightful owners.

  • Not to be reproduced or distributed without explicit permission.
  • Not used for commercial purposes outside of approved use cases.
  • Not used to infringe on the rights of the original creators.
  • If you believe any content infringes your copyright, please contact us immediately.

Support

For help with questions, suggestions, or problems, please contact us