Relative position of 2 points on a circle
2

Question

Relative position of 2 points on a circle

ziggyS (Computer)

(OP)

14 Mar 15 21:01

hi
this question was addressed in thread770-356581: Add or subtract polar degrees in Excel but the resulting formula is only valid for points within 90 degrees of each other

stevenal (Electrical) 21 Jan 14 20:12
'=DEGREES(ASIN(SIN(RADIANS(A1-A2))))'
Excel

recap if point A1 is at position 358 degrees
point A2 is at position 01 degrees
above formula returns -3 (position of A1 relative to A2)

but if point A1 is at position 180 degrees
point A2 is at position 01 degree
above formula returns +1 (required return is +179)

can anyone expand on above formula to be valid over complete circle (+- 180)

thanks
ziggyS

ziggyS (Computer) · Answer 1 · 2015-03-14 21:12:57

i have changed formula to
'=DEGREES(ACOS(COS(RADIANS(A1-A2))))'
which returns the correct whole number but i lose the polarity

IDS (Civil/Environmental) · Answer 2 · 2015-03-14 22:29:14

This should work (it works for your examples):

=DEGREES(ATAN2(COS(RADIANS(A1-A2)),SIN(RADIANS(A1-A2))))

There may be a simpler way, but I doubt it can be done with just sin or just cos.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

ziggyS (Computer) · Answer 3 · 2015-03-14 22:46:56

RE: Relative position of 2 points on a circle

ziggyS (Computer)

(OP)

14 Mar 15 22:46

thanks IDS absolutely perfect!

Come Join Us!

Posting Guidelines

Related Projects

Jobs

Relative position of 2 points on a circle
2