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skr_girl · Mar 27, 2007, 08:29 AM

If α, β are acute angles such that Sin = 1/12 and Cos β = 4/5

Calculate the six trigonometric functions for the sum and differences of the two angles….

vrooje · Mar 28, 2007, 01:35 PM

Did you mean $\sin \alpha = 1/12$ ? There's no angle in the first one, and I'm going to assume you meant $\sin\alpha$ .

Do you have trig identities for the sum and difference of angles? e.g. $\cos\left(\alpha + \beta\right) = \cos(\alpha)\cos(\beta) - \sin(\alpha)\sin(\beta)$ and such?

I suggest that you think of the givens in terms of right triangles, and use SOHCAHTOA and the pythagorean theorem to find $\cos\alpha$ and $\sin\beta$ .

Then use the identities to compute the sine and cosine of the summed and differenced angles, and from there try to get all six trigonometric functions.