$\begingroup$
My answer here is d only because I graphed the piecewise function and tried to plug in the choices. None of the given values make the function continuous for all x. Is my answer right? Is there a way to solve this without graphing?
$\endgroup$ 21 Answer
$\begingroup$Observe the definitions of the pieces in which the function is defined.
$2-sinx$ as well as $cx\sqrt{x^2+2}+c$ are continuous in their domains. So we need to check the continuity only at $x=1$. So, by equating both the sides of the function at $x=1$, we have:
$$2-sin1=c\sqrt3+c$$
$$c\approx0.424$$
$\endgroup$