tolong dijawab menggunakan cara!!

8. 1/4 x phi x r x r
1/4 x 3,14 x 30 x 30
1/4 x 3,14 x 900
314 x 9 : 4 = cek pake kalkulator ya gan

9. rumus = 1/2 x a+b x t
1/2 x 34 + 26 x 20 = 60 x 20 : 2 = 1200 : 2 = 600 = C

10. 1/2 x d1 x d2
36 x 48 : 2 = .... : 2 = ... cek pake kalkulator gan

semoga membantuu