Find all points where the tangent line has slope 1. Let $f(x)=x-\cos(x)$. Find all points on the graph of $y=f(x)$ where the tangent line has slope 1.  (In each answer $n$ varies among all integers).
So far I've used the Sum derivative rule for which I have $1+\sin(x)$. So do I put in 1 in for $x$ for sin$(x)$.
Please Help!!

$f(x) = x - \cos x \tag{1}$
$f'(x) = 1 + \sin x \tag{2}$
$f'(x) = 1 \Rightarrow 1 = 1 + \sin x \Rightarrow \sin x = 0 \tag{3}$
$\sin x = 0 \Leftrightarrow  x = k\pi, \tag{4}$
for $k \in \Bbb Z$, the set of integers.
Hope this helps.  Cheerio, 
and, as always, 
Fiat Lux!!!
