I've been asked to find the area under a graph of a function with limits $\displaystyle (0\leq x \leq 2 \pi )$

I've found just one solution (the other solution turned out impossible as it was outside the limits for arcos) for a stationary point which is a local maximum, so do I just use zero as a local minimum for $\displaystyle x$ to find the area?

Any help is appreciated.