find the area of a circle of radius 35 cm.if a sector of angle 80° is removed from the circle, what area is left
Area of sector, A1 = (1/2).r^2.theta, where theta = 80 degrees = (80/180)*pi radians, giving A1 = pi.r^2(2/9)
Area of circle, A2 = (1/2).r^2.theta, where theta = 2pi, giving A2 = pi.r^2
Area left, A3 = A2 - A1 = pi.r^2 - (2/9)pi.r^2 = (7/9)pi.r^2
Using r = 35 cm,
A3 = (7/9)pi*1225
A3 = 952.78.pi cm^2 = 2,993.24 cm^2 Area of circle = A2 = 1225.pi cm^2 = 3,848.45 cm^2