# Math Help - Sum and Difference Formulas

1. ## Sum and Difference Formulas

For Sin and Cos are easy but what about Sec?

Ex) Sec(-pi/12)

what would the sum and difference formula look like?

2. Originally Posted by gabrie30
For Sin and Cos are easy but what about Sec?

Ex) Sec(-pi/12)

what would the sum and difference formula look like?
$\frac{1}{\cos \left( \frac{\pi}{4} - \frac{\pi}{3} \right)}$.

3. Originally Posted by mr fantastic
$\frac{1}{\cos \left( \frac{\pi}{4} - \frac{\pi}{3} \right)}$.

Right, but what if you had to find the exact value? What would the formula look like?

4. you need to simplify the bottom of the fraction that mr fantastic gave you.

go here: Table of Trigonometric Identities

Look under "Sum-Difference Formulas"

Then pick the second one that involves Cos.