$[f(g(x))]' = f'(g(x)) \cdot g'(x)$

$(\frac{f}{g})' = \frac{gf' - fg'}{g^2}$,      $(\frac{H}{L})' = \frac{LH' - HL'}{L^2}$

$(fg)'= f'g + fg'$

$(x^n)' = nx^{n-1}$,      $(sin(x))' = cos(x)$,      $(cos(x))' = -sin(x)$

from the unit circle: $sin^2(x) + cos^2(x) = 1$

from the graph: $sin(x + \frac{\pi}{2}) = cos(x)$,      $cos(x - \frac{\pi}{2}) = sin(x)$

Optional: $sin(-x) = -sin(x)$,      $cos(-x) = cos(x)$

Slope formulas