(1)
given diameter = 20.4 then r = 10.2
the area( A ) of a circle = πr² ( r is the radius )
A = 3.14 × 10.2² = 326.7 cm² ( to 1 dec. place )
(2)
the area(A) of a sector = area of circle × fraction of circle
A = 3.14 × 10² ×
= (3.14 × 100 × 60) / 360 = 52.3 cm² ( to 1 dec. place )
(3)
A = π ×12² ×
= (π × 144 × 60 ) / 360 = 24π