72. Diagonals of two faces are drawn from the same vertex of a cube. Find the magnitude of the angle between these diagonals.
72. By connecting the ends of the diagonals with a segment, we obtain an equilateral triangle (Fig. 7). Therefore, the angle between the specified diagonals contains \(60^{\circ}\).

## Fig. 7

![](https://cdn.mathpix.com/cropped/2024_05_21_a21e90374409a05a4ea7g-20.jpg?height=300&width=345&top_left_y=1846&top_left_x=867)