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August 31st, 2011, 06:51 PM  #1 
Newbie Joined: Aug 2011 Posts: 3 Thanks: 0 
I love elitist math textbook authors who don't show you how to do the homework problems in the examples. Anyways, I'm seeing problems like this come up in the homework for degrees minutes seconds (dms) and decimal degrees (dd). I have to convert, for example, 57.68 deg to degrees minutes seconds. My answers are coming out off from the ones in the back of the book. For example, 45 deg 6' is, somehow, 44.9 dd? Okay, if I write the problem like this: 45 deg + 6/60' = 45 deg + 0.1 deg = 44.9 dd then it makes sense. However, when I take it back the other way (to dms), I'm screwing something up. In this case... 44.9 deg = 44 deg + 0.9(60') = 44 deg + 54' = 43 deg 6' != 45 deg 6' What am I doing wrong with this relatively simple calculation? Last edited by skipjack; April 16th, 2015 at 06:19 PM. 
August 31st, 2011, 07:05 PM  #2 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,814 Thanks: 1046 Math Focus: Elementary mathematics and beyond  Re: Trig: Converting negative decimal degrees to deg/min'sec
44.9° = (44 +9/10) = (44 +54/60) = 44°  54' = 45° 6'.

August 31st, 2011, 08:25 PM  #3 
Newbie Joined: Aug 2011 Posts: 3 Thanks: 0  Re: Trig: Converting negative decimal degrees to deg/min'sec
Alright, I follow you there  I'm supposed to negate ALL the elements of the dms figure. So, say 60deg50'20" = 60deg  50'  20" is correct? Also, if that's how it works, how is the initial conversion correct? or is it? So... 45 deg 6' = 45 deg + 6/60' = 45 deg + 0.1 deg = 44.9 dd should be 45 deg 6' = (45 deg + 6/60') = (45deg + 0.1 deg) = 45deg  0.1 deg = 45.1 dd != 44.9 dd What did I just do wrong there? 
September 1st, 2011, 05:49 AM  #4 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,814 Thanks: 1046 Math Focus: Elementary mathematics and beyond  Re: Trig: Converting negative decimal degrees to deg/min'sec
You're using different negative/positive values. 45 deg 6' = (45 deg  6/60') = (45deg  0.1 deg) = 45deg + 0.1 deg = 44.9 dd or 45 deg 6' = 45 + 6/60 = 45 + 1/10 = 44.9 dd. They're using different signs for deg and ' (and that seems unusual). 
September 1st, 2011, 09:44 AM  #5 
Newbie Joined: Aug 2011 Posts: 3 Thanks: 0  Re: Trig: Converting negative decimal degrees to deg/min'sec
The deg is because I'm new to this site and I'm too lazy to hunt around in character map for the actual degree symbol. Thanks for the help, Greg!

April 16th, 2015, 01:26 PM  #6 
Global Moderator Joined: May 2007 Posts: 6,526 Thanks: 588 
44=.9 deg = 44deg  .9(60)' etc. You had + instead of .


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