# How to get the sum of functions

I'm having a tough time with this question:

$f(x) = -3 + 2\cos(x)$

$g(x) = \cos(x- \frac{\pi}4) -2$

Sum of functions: $s(x) = f(x) + g(x)$ Difference of functions: $v(x) = f(x)-g(x)$

Get the sum of functions and the difference of functions (both sinusoids), round off to 2 decimal places. We are allowed to use the Ti=84+ (so we can use calc max, calc intersect, etc.)

The answers are:
$s(x) = -5 + 2.80\cos(x – 0.26)$

$v (x) = -1 + 1.47\sin (x – 4.21)$

• ps - Also please correct my terminology, I want to learn how to say mathematical terms and such in english.
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When you wrote $1/4\pi$ did you mean $1/(4\pi)$ or $(1/4)\pi$? – rschwieb Sep 11 '12 at 20:17
(1/4)π 8moretogo – TimFrankerburg Sep 11 '12 at 20:33