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Perhatikan gambar gabungan kerucut dan tabung beri...

Perhatikan gambar gabungan kerucut dan tabung berikut!


 


Luas permukaan bangun tersebut adalah ...space 

  1. begin mathsize 14px style 704 space cm squared end style 

  2. begin mathsize 14px style 1.078 space cm squared end style 

  3. begin mathsize 14px style 1.232 space cm squared end style 

  4. begin mathsize 14px style 1.386 space cm squared end style 

Jawaban:

Bagian bawah bangun ruang berbentuk tabung tanpa tutup dengan;

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row straight d equals cell 14 space cm end cell row straight r equals cell 1 half cross times straight d end cell row blank equals cell 1 half cross times 14 end cell row blank equals cell 7 space cm end cell row straight t equals cell 12 space cm end cell row blank blank blank row cell straight L subscript permukaan end cell equals cell πr squared plus 2 πrt end cell row blank equals cell 22 over 7 cross times 7 squared plus 2 cross times 22 over 7 cross times 7 cross times 12 end cell row blank equals cell 22 cross times 7 plus 2 cross times 22 cross times 1 cross times 12 end cell row blank equals cell 154 plus 528 end cell row blank equals cell 682 space cm squared end cell end table end style 

Bagian atas tabung berbentuk selimut kerucut dengan 

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row straight d equals cell 14 space cm end cell row straight r equals cell 1 half cross times 14 end cell row blank equals cell 7 space cm end cell row straight t equals cell 36 minus 12 end cell row blank equals cell 24 space cm end cell row blank blank blank row straight s equals cell square root of straight r squared plus straight t squared end root end cell row blank equals cell square root of 7 squared plus 24 squared end root end cell row blank equals cell square root of 49 plus 576 end root end cell row blank equals cell square root of 625 end cell row blank equals cell 25 space cm end cell row blank blank blank row cell straight L subscript selimut space kerucut end subscript end cell equals πrs row blank equals cell 22 over 7 cross times 7 cross times 25 end cell row blank equals cell 550 space cm squared end cell end table end style 

Maka luas permukaan bangun tersebut adalah 

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell straight L subscript permukaan end cell equals cell straight L subscript permukaan space tabung end subscript plus straight L subscript selimut space kerucut end subscript end cell row blank equals cell 682 plus 550 end cell row blank equals cell 1.232 space cm squared end cell end table end style 

Jadi jawaban yang tepat adalah C.   

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