# Math Help - The Addition and subtraction Formulas

1. ## The Addition and subtraction Formulas

If $sin \alpha = \frac{-5}{13}$ and tan is less than 0, find the exact value of $sin (\alpha-\frac{\pi}{3})$

How do you find the exact value do you use the Sine of differences or do you use the cofunction identities for any real number t?

2. Originally Posted by purplec16
If $sin \alpha = \frac{-5}{13}$ and tan is less than 0, find the exact value of $sin (\alpha-\frac{\pi}{3})$

How do you find the exact value do you use the Sine of differences or do you use the cofunction identities for any real number t?
$sin(A-B) = sinA*cos B - cosA*sinB$

Use your given values of A and B in the above equation and you should have your answer.

Keep in mind that :

$\cos A = \sqrt{1-sin^{2}A}$