My Math Forum Finding arc length

 Geometry Geometry Math Forum

 November 14th, 2016, 06:49 AM #1 Newbie   Joined: Nov 2016 From: Canada Posts: 1 Thanks: 0 Finding arc length I want to find the length of an arc with the following data: XYZ coordinates of start point XYZ coordinates of center point of the arc XYZ coordinates of end point arc direction Radius I can find the chord but there is 2 possible arcs with these values The arc is on a plane (XY,XZ,YZ) but I dont know which one Last edited by VincentP; November 14th, 2016 at 07:46 AM.
 November 14th, 2016, 12:21 PM #2 Senior Member     Joined: Sep 2015 From: Southern California, USA Posts: 1,500 Thanks: 757 well as you've said there are two arcs that meet those conditions. fortunately if you know the arc length of one, $\ell_1$, the arc length of the other is just $\ell_2 = 2\pi r - \ell_1$
 November 14th, 2016, 01:44 PM #3 Global Moderator   Joined: May 2007 Posts: 6,343 Thanks: 534 If you know the coordinates of the center point of the arc, this will tell you which of the 2 possible arcs defined by the chord. This can be done by examining the chord from the end point to the midpoint of the arc. Compare it to $\displaystyle \frac{r\sqrt{2}}{2}$. Less is the shorter angle, more is the longer angle. Last edited by mathman; November 14th, 2016 at 01:46 PM.

 Tags arc, finding, length

 Thread Tools Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Matthew Trigonometry 8 January 10th, 2015 10:50 AM unistu Geometry 5 January 7th, 2015 07:39 PM xnarutox Algebra 4 October 2nd, 2010 10:04 AM lefucer Real Analysis 1 September 1st, 2008 08:35 AM lefucer Calculus 1 March 22nd, 2008 03:32 PM

 Contact - Home - Forums - Cryptocurrency Forum - Top