A chord of a circle of radius 12 cm subtends an angle of 120° at the centre. Find the area of the corresponding segment of the circle
(Use π = 3.14 and √3 = 1.73)
Let us draw a perpendicular OV on chord ST. It will bisect the chord ST and the angle O.
SV = VT
In ΔOVS,
= Cos 60o
=
OV = 6 cm
= Sin 60o
=
SV = 6√3 cm
ST = 2 * SV
= 2 * 6√3
= 12√3 cm
Area of ΔOST = * 12√3 * 6
= 36√3
= 36 * 1.73
= 62.28 cm2
Area of sector OSUT = * π * (12)2
= * 3.14 * 144
= 150.72 cm2
Area of segment SUT = Area of sector OSUT - Area of ΔOST
= 150.72 - 62.28
= 88.44 cm2