Originally Posted by

**Lambin** Is there a general approach for solving functions that contain both trig. and algebraic terms? And to be more specific, how does it apply for a problem like this:

$\displaystyle f(x)=x^3+2x+tanx$

In problems with trig. functions, I'm able to determine that for $\displaystyle sin(x)=cos(x)$, $\displaystyle x$ is equal to $\displaystyle \frac{\pi}{4}, \frac{5\pi}{4}$ because it corresponds to an isosceles triangle on the unit circle with equal sides of lengths $\displaystyle cos(x)$ and $\displaystyle sin(x)$, but it wasn't a direct proof.