kalau gk jelas bilang.pakai cara

no 7
πr^2= 22/7 x 7x7 = 22x7= 154
no 8
d=10,maka r=5
πr^2
=22/7x5x5
=78.57142857143
no 9
1/2π+p x l
=1/2x22/7+8x2
=17.57142857143