jawaban yaaa plsplsplsss:

3. v setengah bola = 1/2 x 4/3 x 22/7 x 21 x 21 x 21 = 19.404
    v tabung = 22/7 x 21 x 21 x 21 = 29.106
    v kerucut = 1/3 x 22/7 x 21 x 21 x 21 x 30 = 13.860
    v total = 62.370 cm³
4. L selimut kerucut = π r s   ( s = √(21²) + (28²) = √1225 = 35
                                       = 22/7 x 21 x 35 =1386
    L selimut tabung = 2 π r t = 2. 22/7. 21. 21 = 2772
    1/2 luas bola       = 1/2 . 4 . π. r² =  2772
     total = 6930 cm²