tolong dijawab bsk dikumpulin

[tex]1.kel = \frac{22}{7} \times 28 = 88 \: cm [/tex]
[tex]2.kel = 2 \times 3.14 \times 20 = 125.6[/tex]
[tex]3.luas = 3.14 \times 12 \times 12 = 452.16[/tex]
[tex]4.luas = \frac{1}{4} \times 3.14 \times 40 \times 40 = 1256[/tex]
[tex]5.2000 \times 2 \times \frac{22}{7} \times 21 = 528.000[/tex]

jadikan jawaban terbaik yaa^_^