Many people refer to a 45-degree corner as a bullnose corner since these corners are often rounded. Like a 90-degree corner, you cover a 45-degree corner with a corner bead. However, you hang the drywall slightly differently on a 45-degree corner than you do on a 90-degree corner. On a 90-degree corner, the drywall can overlap slightly, but on a 45-degree corner the drywall cannot overlap and must stop at the wall stud's corner. This ensures that the 45-degree corner bead can be tightly secured to both pieces of drywall and make a perfect curve.
Measure the distance from the last piece of drywall to the 45-degree corner's stud. Transfer this measurement to the top and bottom of a piece of drywall. Use a straightedge and a utility knife to score the drywall's surface. Tap the drywall's back side to break it, and use the utility knife to cut through the drywall's paper backing.
Position the cut drywall into the measured space. Make sure the drywall's end is flush with the wall stud's end. Use a drill and Phillips driving bit to drive drywall screws through the drywall and into the studs. Embed the screw heads slightly so you can easily hide them with drywall mud during the taping and finishing process.
Lift a piece of drywall up to the wall and position it on the other side of the 45-degree corner. Measure and cut this sheet of drywall the same way you did the first sheet, if necessary. Position the second piece of drywall's edge flush against the wall stud's edge. Do not overlap the edge with the first piece's edge. Drive drywall screws through the second piece of drywall and into the wall studs.
Repeat steps 1 through 3 for a second row of drywall. Make sure the second row's bottom edge sits tightly on the first row's top edge. Do not overlap the drywall at the 45-degree corner. Hang a third row in the same way, if necessary.
Measure the corner's height, from the ceiling to the floor, and transfer this measurement to a 45-degree corner bead. Use a metal snips to cut the corner bead to the appropriate length. Position the corner bead over the 45-degree corner. Use drywall screws to secure the corner bead to the drywall.
If you use rounded 45-degree corner beads, put a 90-degree adaptor at the bottom to make it easier to install baseboard moulding.