Use of cosinus for calculation of a triangle

[Whuggy]

Hello,
I'm having a problem getting excel to calculate the angles of a triangle.

I know the formula for calculating angle C for instance (knowing lengths of
all three sides)

cosinus^-1 of (a^2+b^2-c^2)/(2*a*b)

But how do I put this into excel? When I put it in as following:
COS^1((a^2+b^2-c^2)/(2*a*b)) It dosn't work.

Can anybody help me?

Thanks

 

[Bernie Deitrick]

Whuggy,

With a in A2, b in B2, and c in C2, the value of C in degrees is

=ACOS((A2^2+B2^2-C2^2)/(2*A2*B2))*180/(PI())

and in radians is

=ACOS((A2^2+B2^2-C2^2)/(2*A2*B2))

HTH,
Bernie
MS Excel MVP

 

[Pete_UK]

The result will be in radians - there are 2 x pi radians in 360
degrees.

Hope this helps.

Pete

 

[Whuggy]

Thanks a lot for the answer. Just what I needed!

Whuggy,

With a in A2, b in B2, and c in C2, the value of C in degrees is

=ACOS((A2^2+B2^2-C2^2)/(2*A2*B2))*180/(PI())

and in radians is

=ACOS((A2^2+B2^2-C2^2)/(2*A2*B2))

HTH,
Bernie
MS Excel MVP