Why doesn't this trigonometric integral evaluate? I'm trying to follow this Wolfram Alpha derivation (click "Show steps"...) of an integral question I posted earlier.  My question is specifically, the second last line (before they use "an equivalent for restricted t values") is:
$$
\left. -\frac{2}{3} \sqrt{ 1 - \cos{3\theta} }\,\, \right|_0^{2\pi}
$$
But why doesn't the definite integral work out to the correct answer (listed under "Definite integral over a period:", near the bottom) of $ 4 \sqrt{2} $?
When you plug in the limits, you get $ - \frac{2}{3} ( 0 - 0 ) $ which is just $0$.
Edit: You have to click "Try again with more time" for this to appear, but here is the "definite integral over a period":


In the item you posted earlier, there was an absolute value.  $0$ is just what you would get if that were neglected.  So I suspect it was neglected.
