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         Trigonometry:     more books (105)
  1. Plane Trigonometry by E. Richard Heineman, J. Dalton Tarwater, 1993-01-01
  2. Precalculus with Trigonometry: Concepts and Applications, Solutions Manual by Paul Foerster, 2006-05-31
  3. Plane and Spherical Trigonometry (Classic Reprint) by George N. Bauer, 2010-09-20
  4. Precalculus: With Unit Circle Trigonometry (with CD-ROM and iLrn? Tutorial) by David Cohen, 2005-03-21
  5. Graphical Approach to Algebra and Trigonometry, A (5th Edition) (Hornsby/Lial/Rockswold Graphical Approach Series) by John Hornsby, Margaret L. Lial, et all 2010-02-06
  6. Algebra & Trigonometry Enhanced with Graphing Utilities (2nd Edition) by Michael Sullivan, Michael J Sullivan, 1999-10-06
  7. Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (2nd Edition) (Sullivan Concepts Through Functions Series) by Michael Sullivan, Michael Sullivan III, 2010-02-26
  8. Trigonometry the Easy Way by Douglas Downing Ph.D., 2001-02-01
  9. Trigonometry (2nd Edition) by Judith A. Beecher, Judith A. Penna, et all 2007-10-20
  10. Trigonometry: A Unit Circle Approach (8th Edition) by Michael Sullivan, 2007-05-18
  11. Schaum's Outline Series : Theory and Problems of Plane and Spherical Trigonometry (including 680 problems solved in detail) by Frank Ayres jr, 1954-12
  12. Student Solutions Manual College Algebra with Trigonometry by Raymond Barnett, Michael Ziegler, et all 2010-04-14
  13. Teach Yourself Trigonometry by P.Abbott, 2003-07-28
  14. Algebra 2 With Trigonometry by Be Hall, 1993-06

81. Lecture 5: Stellar Distances
This means that from the ground, the method of Trigonometric Parallaxes has the following limitations. good out to 100 pc; only get 10% distances out to a
Astronomy 162:
Prof. Richard Pogge, MTWThF 9:30
Lecture 5: Distances of the Stars
Readings: Ch 19, section 19-1
Key Ideas
Method of Trigonometric Parallaxes
Direct geometric method of finding distances
Units of Cosmic Distance:
Light Year
Parsec ( Par allax sec ond)
Why are Distances Important?
Distances are necessary for estimating:
  • Total energy emitted by an object (Luminosity)
  • Masses of objects from their orbital motions
  • True motions through space of stars
  • Physical sizes of objects
The problem is that distances are very hard to measure...
The problem of measuring distances
How do you measure the distance of something that is beyond the reach of your measuring instruments?
Examples of such problems:
  • Military range finding to targets
  • Measuring distances to any astronomical object
You resort to using GEOMETRY to find the distance.
The Method of Trigonometric Parallaxes
Nearby stars appear to move with respect to more distant background stars due to the motion of the Earth around the Sun. This apparent motion (it is not "true" motion) is called Stellar Parallax
(Click on the image to view at full scale [Size: 7Kb]) In the picture above, the line of sight to the star in December is different than that in June, when the Earth is on the other side of its orbit. As seen from the Earth, the nearby star appears to sweep through the angle shown. Half of this angle, is the parallax

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