# What does 2sin(arccos(4))-cos(arc sin(3)) equal?

If we are not using complex numbers, then $\arccos \left(4\right)$ and $\arcsin \left(3\right)$ are both undefined, as there is no real number $x$ such that $\cos \left(x\right) = 4$ or $\sin \left(x\right) = 3$.