
Trigonometry Trigonometry Math Forum 
 LinkBack  Thread Tools  Display Modes 
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: 7,842 Thanks: 1068 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: 7,842 Thanks: 1068 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: 6,560 Thanks: 604 
44=.9 deg = 44deg  .9(60)' etc. You had + instead of .


Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
How to calculate the "degrees" of this matrix?  leo75  Algebra  2  June 25th, 2013 01:42 PM 
Converting radians to degrees  hemidol  Algebra  1  April 8th, 2012 07:19 PM 
Converting Vice Versa from Radian to Degrees  David_Lete  Algebra  3  April 26th, 2009 03:32 PM 
Problem with basic trig (degrees/radians)  9nuza0902  Algebra  2  October 29th, 2008 03:56 PM 
Difference between a negative number and decimal number?  zain  Elementary Math  2  April 26th, 2008 01:07 PM 