Diketahui sebuah tabung memiliki luas permukaan 2.552 cm2 dan tinggi 25 cm. Hitunglah jari-jari tabung tersebut!

Pertanyaan

Diketahui sebuah tabung memiliki luas permukaan $2.552\;\mathrm{cm}^2$ dan tinggi $25\;\mathrm{cm}$ . Hitunglah jari-jari tabung tersebut!

S. Yoga

Master Teacher

Mahasiswa/Alumni Universitas Pendidikan Indonesia

Jawaban terverifikasi

Jawaban

jari-jari tabung tersebut adalah 11 comma 2 space cm

Pembahasan

Diketahui:

luas permukaan 2.552 space cm squared dan tinggi 25 space cm .

Mencari jari-jari:

$table attributes columnalign right center left columnspacing 0px end attributes row Lp equals cell 2 πr left parenthesis straight r plus straight t right parenthesis end cell row 2552 equals cell 2 times 22 over 7 times straight r open parentheses straight r plus 25 close parentheses end cell row cell fraction numerator 44 straight r squared over denominator 7 end fraction plus fraction numerator 1100 straight r over denominator 7 end fraction end cell equals 2552 row cell fraction numerator 44 straight r squared over denominator 7 end fraction plus fraction numerator 1100 straight r over denominator 7 end fraction minus 2552 end cell equals 0 row cell straight r subscript 1 comma thin space 2 end subscript end cell equals cell fraction numerator negative 1100 over 7 plus-or-minus square root of open parentheses 1100 over 7 close parentheses squared minus 4 times 44 over 7 open parentheses negative 2552 close parentheses end root over denominator 2 times 44 over 7 end fraction end cell row cell straight r subscript 1 comma thin space 2 end subscript end cell equals cell fraction numerator negative 1100 over 7 plus-or-minus fraction numerator 44 square root of 2249 over denominator 7 end fraction over denominator 2 times 44 over 7 end fraction end cell row cell straight r subscript 1 end cell equals cell fraction numerator negative 1100 over 7 plus fraction numerator 44 square root of 2249 over denominator 7 end fraction over denominator 2 times 44 over 7 end fraction comma thin space straight r subscript 2 equals fraction numerator negative 1100 over 7 minus fraction numerator 44 square root of 2249 over denominator 7 end fraction over denominator 2 times 44 over 7 end fraction end cell row straight r equals cell fraction numerator negative 25 plus square root of 2249 over denominator 2 end fraction comma thin space straight r equals negative fraction numerator 25 plus square root of 2249 over denominator 2 end fraction end cell row straight r equals cell 11 comma 2 comma space straight r equals negative 36 comma 2 end cell end table$

Karena suatu panjang tidak mungkin negatif, sehingga straight r equals 11 comma 2 space cm .

Jadi, jari-jari tabung tersebut adalah 11 comma 2 space cm .