1.7: Angle between a face of a pyramid and its base

Figure 1 shows a right pyramid $\displaystyle VABCD$ with vertex $\displaystyle V$ and square base $\displaystyle ABCD$. Each of the edges of the pyramid has the same length.

Find the size, in degrees to one decimal place, of the angle between the plane $\displaystyle CVD$ and the base $\displaystyle ABCD$.