Trig help

1. Jan 10, 2007

Fresh4Christ

I have the problem:

0 = 3[cos(35)*cos(A) - sin(35)*sin(A)] - cos(A)
where A is alpha...my unknown degree.

somehow that turns into this:

tan(A) = [cos(35) - 1/3] / sin(35)

I am not drawing the connection or seeing how that is happening....

Could you help???? THANKS

2. Jan 10, 2007

robert Ihnot

Looking at the form we want, the first thing to do is divide by cos(A). Then at that point it is possible to seperate tan(A) from the other terms.

3. Jan 10, 2007

theperthvan

Rearrange to give

$$cos(35).cos(A) - \frac{cos(A)}{3} = sin(35)sin(A)$$

$$cos(A)(cos(35) - \frac{1}{3}) = sin(35).sin(A)$$

divide both sides by $$cos(A)$$ to give

$$(cos(35) - \frac{1}{3}) = sin(35).tan(A)$$

divide both sides by $$sin(35)$$ to give

$$\frac{(cos(35) - \frac{1}{3})}{sin(35)} = tan(A)$$

Last edited: Jan 10, 2007
4. Jan 10, 2007

theperthvan

oops, that y should be A

EDIT: ignore that

Last edited: Jan 10, 2007
5. Jan 10, 2007

Fresh4Christ

Thank you soooo much!