Hello Ron,
I tried your formula and it works well also. I need to study this one.
Thank you for your input. I learn something different.
Serge

"Ron Rosenfeld" wrote:

On Thu, 25 May 2006 18:35:01 -0700, Serge
wrote:

The formula below gives a result of 79.935 degrees using calculator
cos A = (b² + c²) - a² / 2bc
a=25.0 in A57
b=21.5407 in B57
c=17.0 in C57

This formula below has error which I cannot fix.
I have been trying for a while with no luck.
It could be that I'm trying to approch it the same way as a calculator.
In E57
=IF(OR(A57="",B57="",C57=""),0,DEGREES(ACOS(B57^+ C57^)-A57^/2*B57*C57)))

Or in E57 =IF(COUNT(A57:C57)<3,0),0,DEGREES(ACOS(B57^+C57^)-A57^/2*B57*C57)))
My answer should be 79.935 degrees
Does someone have an answer for this puzzle?
Many thanks in advance.
Serge



You just need to properly arrange your parentheses:

=IF(COUNT(A57:C57)=3,DEGREES(ACOS((B57^2+C57^2-A57^2)/(2*B57*C57))),0)

--ron