محيط القطاع ؟؟

-1-

-2-

2*pi is the number of radians for the circle

(120/360)*2*pi=

(120/180)*pi=

(2/3)*pi

Multiply that by the radius and you approximately get

(2/3)*pi*21=43.9822971503

If we include the sides of the radius it is

(2/3)*pi*21+2*21=85.9822971503

 

-3-

-4-