A rotor blade of a turbomachine includes an airfoil. The airfoil includes a root and a tip which define a span of the airfoil therebetween. The airfoil also includes a leading edge and a trailing edge downstream of the leading edge along a flow direction. The leading edge and the trailing edge each extend across the span of the airfoil from the root to the tip. The airfoil further includes a pressure side surface and a suction side surface. The pressure side surface and the suction side surface are continuous about the trailing edge and collectively define an arc centered on the trailing edge. The arc has a semi-major axis and a semi-minor axis. The semi-major axis and the semi-minor axis of the arc define an axis ratio, and the axis ratio varies over the span of the airfoil.