Abstract: An adjustable trowel to facilitate formation of a coved corner between two structural panels comprises a blade having two laterally spaced trapezoidal-shaped, rigid wing segments integrally joined along parallel inside edges by an intermediate segment which is of rectangular shape and of reduced thickness compared to the rigid wing segments to allow flexure in the zone occupied by the intermediate segment. Affixed to each of the rigid wing segments are handle mounting brackets that overlap one another and include an arcuate slot therein for receiving a handle mounting bolt therethrough. By tightening the bolt, the wings are held at a selected angle to one another and with the intermediate segment assuming a desired curvature.