luas bagian 3/4 lingkaran berdiameter 21 adalah

d = 21
r = 21/2
r = 10,5 cm

L 3/4 lingkaran
= 3/4 x phi r²
= 3/4 x 22/7 x 10,5²
= 3/4 x 22/7 x 110,25
= 3/4 x 22 x 15,75
= 3/2 x 11 x 15,75
= 33/2 x 15,75
= 519,75/2
= 259.875 cm²