Sectors are portions of the circle which are similar to pizza slices. The area of a sector is equal to pi * r^2 * theta. Theta here is expressed in radians. Hence we convert 110 degrees to radians ( 110*pi/180) equal to 11 pi / 18. In this case, we substitute:
50 = 11 pi /18 * (r^2) * pi r then is equal to 2.88 units