On Thu, 25 May 2006 18:35:01 -0700, Serge <Serge@discussions.microsoft.com>
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