Bonjour,

formule:

Pir²

a)

( 3,14 * 2,5²)/2 =>9,8 125cm² =9,81cm²

b)

(3,14 * 4²)/4 =12,56cm²

c)

(3,14 * 6²)- (3,14*6²)/4=

113,04 - 6,21 => 106,83 cm²

360/120 =3

=> 1/3 de cercle

(3,14* 3²) /3

= 28,26 /3

= 9,42cm²