tolong jawab ya please besok kumpul

3. a. d = 2 x r = 2 x 5 = 10 cm
        K = pi x d = 3,14 x 10 = 31,4 cm
 
    b. r = d : 2 = 15 : 2 = 7,5 cm
        K = pi x d = 3,14 x 15 = 47,1 cm
  
    c. r = d : 2 = 9 : 2 = 3,5 cm
       K = pi x d = 3,14 x 9 = 28,26 cm
 
   d. d = r x 2= 6,4 x 2 = 12,8 cm
      K = pi x d = 3,14 x 12,8 = 40,192 cm


Semoga membantu