Formula in 2002

[leonperrins]

Can any one help me with inputting the following cosine formula.

a(squared) = b(squared) + c(squared) - 2bc CosA

I want to input various values for sides a & b and angle A.

 

[Dave]

Hi,
To solve for different unknowns, you need to make the unknown the subject of
the formula.
eg, to solve for a:
a=square root(b(squared)+c(squared)-2bc*CosA)
as an XL formula:
=(b^2+c^2-2*b*c*COS(A))^0.5
To make it easier to input values, assign cells to contain the values.
EG.
A1 has a
B1 has b
C1 has c
D1 has A
Then the formula would look like this:
=(B1^2+C1^2-2*B1*C1*COS(D1))^0.5
It's a bit longer, but you don't have to change it each time.
Hope this helps.
Regards - Dave.

 

[Ken Johnson]

Can any one help me with inputting the following cosine formula.

a(squared) = b(squared) + c(squared) - 2bc CosA

I want to input various values for sides a & b and angle A.

Assuming column A for a, column B for b and column D for angle A in
degrees, then in column C...

=SQRT(POWER(A1,2)+POWER(B1,2)-PRODUCT(2,A1,B1,COS(RADIANS(D1))))

Ken Johnson

 

[leonperrins]

Thanks Guys,

Unfortunately both formulae give an error when entered into Excel.

I have assumed that a "SUM" is required at the start of the formula, is this
correct?

If not please show all details for an ageing, forgetful old mathematician.

 

[Ken Johnson]

Thanks Guys,

Unfortunately both formulae give an error when entered into Excel.

I have assumed that a "SUM" is required at the start of the formula, is this
correct?

If not please show all details for an ageing, forgetful old mathematician.

I don't get an error.
Where on the sheet are you entering your a, b and angle A values?
What is the error?
You can use SUM, but not at the start, but it's just not necessary to
use...

=SQRT(SUM(POWER(A1,2),POWER(B1,2),-PRODUCT(2,A1,B1,COS(RADIANS(D1)))))

Ken Johnson

 

[leonperrins]

Thanks Ken,
The modified formula works.

I don't get an error.
Where on the sheet are you entering your a, b and angle A values?
What is the error?
You can use SUM, but not at the start, but it's just not necessary to
use...

=SQRT(SUM(POWER(A1,2),POWER(B1,2),-PRODUCT(2,A1,B1,COS(RADIANS(D1)))))

Ken Johnson