A sector has an area of 30π in.2. The radii containing the sector form an angle of 100°. What is the area of the circle? The ratio of the angle of the sector to the entire circle is . Area of the sector = StartFraction n degrees over 360 degrees EndFraction (pi) (r squared). 30 pi = StartFraction 100 degrees over 360 degrees EndFraction (pi) (r squared). (StartFraction 18 over 5 EndFraction) 30 pi = (pi) r squared. The area of the entire circle is Pi in.2