Converting Radians to Degrees, Minutes, Seconds

[nathanralph]

I keep coming up with 143 degrees, 18 minutes, 43.5 seconds (44 rounded) but I am told this is incorrect. Why?

 

[stapel]

What is the unit on "2.5"? Is this radians? How are you doing your conversion? What are the steps that you've done?

Eliz.

 

[tkhunny]

2.5 radians * (180/pi) = 143.2394487827 degrees

143.2394487827 degrees = 143 degrees + 0.2394487827 degrees

0.2394487827 degrees * (60 min/1 degree) = 14.36692696 minutes

14.36692696 minutes = 14 minutes + 0.36692696 minutes

0.36692696 minutes * (60 seconds/1 minutes) = 22.0156177 seconds

I don't see how you got 18 minutes.

 

[nathanralph]

Thanks...I was just using 3.14 as pi and it was coming up as 143.31...

 

[tkhunny]

1/2 second = 1/120 minute = 1/7200 degrees = 1/412530 radians

This suggests that if you want to start with "radians" and convert to "seconds", you had better keep track of millionths, 0.000001. pi = 3.14 is gravely inadequate.

Now you know.