Results 1 to 7 of 7
Thread: Triangle Circle Diameter (2k3)

20070717, 13:54 #1
 Join Date
 Jul 2004
 Location
 Ohio
 Posts
 629
 Thanks
 0
 Thanked 0 Times in 0 Posts
Triangle Circle Diameter (2k3)
This is half excel half math help. If i have 1 side of an equilateral triangle  what is the easiest formula to put into excel that will give me the diameter of the circle using the 3 end points of the resultant triangle?
Thanks!<img src=/w3timages/blueline.gif width=33% height=2>
<big>John</big>

20070717, 14:14 #2
 Join Date
 Mar 2002
 Posts
 84,353
 Thanks
 0
 Thanked 28 Times in 28 Posts
Re: Triangle Circle Diameter (2k3)
If you denote the side by s, a little elementary maths shows that the radius of the circle is s / (square root of 3), and the diameter is twice that: 2 * s / (square root of 3). So if you enter the side in cell A1, the formula
=2*A1/SQRT(3)
will return the diameter.

20070717, 14:15 #3
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
Re: Triangle Circle Diameter (2k3)
If A1 has the length:
=A1/COS(PI()/6)
(pi/6 = 30

20070717, 14:26 #4
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
Re: Triangle Circle Diameter (2k3)
I suppose even "easier" than both Hans and my equation is:
=1.1547*A1
if you are happy with 6 sig figs (the 1.1547 is actually 1.1547<font color=red>0</font color=red>, Of course you can simplify it further by reducing the sig figs accordingly(1.155*A1, 1.15*A1, 1.2*A1 or even just =A1 if you are happy with just 1 sig fig... <img src=/S/smile.gif border=0 alt=smile width=15 height=15>
Steve

20070717, 14:32 #5
 Join Date
 Mar 2002
 Posts
 84,353
 Thanks
 0
 Thanked 28 Times in 28 Posts
Re: Triangle Circle Diameter (2k3)
And here is a picture...

20070717, 16:53 #6
 Join Date
 Jul 2004
 Location
 Ohio
 Posts
 629
 Thanks
 0
 Thanked 0 Times in 0 Posts
Re: Triangle Circle Diameter (2k3)
Thanks Hans & Steve you've both made it clear as mud <img src=/S/laugh.gif border=0 alt=laugh width=15 height=15>
just kidding, thanks!<img src=/w3timages/blueline.gif width=33% height=2>
<big>John</big>

20070717, 18:27 #7
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
Re: Triangle Circle Diameter (2k3)
Here is my picture for the solution
Steve
PS cos(30