Tutorial 11 Circular Measure 1. In the diagram, OAB is a sector of a circle with centre O and radius 8 cm. Angle BOA is αradians. OAC is a semicircle with diameter OA. The area of the semicircle OAC is twice the area of the sector OAB. (i) Find αin terms of π. (ii)Find the perimeter of the complete figure in terms of π.2. The diagram shows a square ABCD of side 10 cm. The mid-point of AD is O and BXC is an arc of a circle with centre O. (i) Show that angle BOC is 0.9273 radians, correct to 4 decimal places. (ii) Find the perimeter of the shaded region. (iii) Find the area of the shaded region.