1. ## trigonometry: simplifying

cos^2C-sin^2C/cosC - sinC

C is an angle

thanks so much

2. Originally Posted by fotzefotze
cos^2C-sin^2C/cosC - sinC

C is an angle

thanks so much
Hey fotzefotze,

If it looks like this: $\frac{cos^2C-sin^2C}{(cosC - sinC)}$

Then: $\frac{(cosC+sinC)(cosC-sinC)}{(cosC - sinC)} = (cosC+sinC)$

tsal15

Could you please explain why that last step simplifies that way? thanks.

4. Originally Posted by fotzefotze
Could you please explain why that last step simplifies that way? thanks.
I'm canceling the particular numerator with the denominator.

I'll give u a similar example,

$\frac{x^2 -9}{x-3} = \frac{(x-3)(x+3)}{(x-3)} = (x+3)$ lets say $x = 4$ and substitute it in the original equation to check, $\frac{((4)^2-9)}{((4)-3)} = 7$ and now sub it into $(x+3) = 7$

let me know if u need more help...

5. Alright. I completely get it now. thanks

6. welcome