find dy/dx when x=2 if
y=cos-1 (x)
i understand that -1 du
squrt 1-u^2 dx
but now i will get a negative number at the bottom and i cant get a square root of a negative number thank you 4 your time
$\displaystyle x = 2$ is not in the domain of the inverse trig function $\displaystyle y = \cos^{-1}{x}$.
the domain is $\displaystyle -1 \leq x \leq 1$
you sure it isn't ...
$\displaystyle y = (\cos{x})^{-1} = \frac{1}{\cos{x}} = \sec{x}$ ?