Which type of casket is described as having vertical sides at right angles to the bottom?

The type of casket characterized by having vertical sides at right angles to the bottom is the state casket. This design typically features a rectangular shape with straight, vertical sides, making it easily distinguishable from other casket styles.

State caskets are often associated with formal ceremonies and are selected for their gravitas and elegant appearance. They usually have a classic design, which can complement various funeral settings and serve to honor the deceased appropriately. The structure allows for a spacious interior, accommodating the needs of the deceased comfortably.

In contrast, urn-shaped caskets exhibit a tapering design reminiscent of traditional urns, while octagon caskets have eight sides, which diverges significantly from the vertical rectangular shape. Flaring square caskets consist of sides that angle outward, differing from the rigid vertical characteristics of the state casket. Thus, the distinct vertical and perpendicular construction of the state casket makes it the correct answer in this context.