Tabung luas permukaan = 16.500 2 x π x r x (r + t) = 16.500 2 x (22/7) x r x (r + 40) = 16.500 r² + 40r = 16.500 x 7/44 r² + 40r = 2.625 r² + 40r - 2.625 = 0 (r + 75) (r - 35) = 0 r + 75 = 0 r = -75 (tidak memenuhi karena negatif)
r - 35 = 0 r = 35 (memenuhi karena positif)
r = 35 cm
luas tutup tabung = π x r x r = (22/7) x 35 x 35 = 3.850 cm²
✩✩ C ✩✩
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BintangThoriq
maaf, tp rumus (r+t) tu dr mana ya, saya masih kurang paham
Verified answer
Bab Bangun RuangMatematika SMP Kelas VIII
Tabung
luas permukaan = 16.500
2 x π x r x (r + t) = 16.500
2 x (22/7) x r x (r + 40) = 16.500
r² + 40r = 16.500 x 7/44
r² + 40r = 2.625
r² + 40r - 2.625 = 0
(r + 75) (r - 35) = 0
r + 75 = 0
r = -75 (tidak memenuhi karena negatif)
r - 35 = 0
r = 35 (memenuhi karena positif)
r = 35 cm
luas tutup tabung
= π x r x r
= (22/7) x 35 x 35
= 3.850 cm²
✩✩ C ✩✩