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Pertanyaan

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Besar begin mathsize 14px style angle CBA end style adalah ....

  1. begin mathsize 14px style 40 degree end style 

  2. size 14px 45 size 14px comma size 14px 5 size 14px degree 

  3. size 14px 72 size 14px comma size 14px 5 size 14px degree 

  4. begin mathsize 14px style 77 degree end style 

Pembahasan Soal:

Jumlah sudut dalam segitiga adalah begin mathsize 14px style 180 degree end style.

Jumlah sudut berpelurus adalah begin mathsize 14px style 180 degree end style.

Perhatikan bahwa begin mathsize 14px style angle CAB space dan space angle DAB end style adalah sudut berpelurus sehingga dapat diperoleh:

begin mathsize 14px style table attributes columnalign right center left columnspacing 2px end attributes row cell straight m angle CAB plus straight m angle DAB end cell equals cell 180 degree end cell row cell open parentheses 2 y plus 8 degree close parentheses plus 140 degree end cell equals cell 180 degree end cell row cell open parentheses 2 y plus 8 degree close parentheses end cell equals cell 180 degree minus 140 degree end cell row cell 2 y end cell equals cell 40 degree minus 8 degree end cell row y equals cell fraction numerator 32 degree over denominator 2 end fraction end cell row y equals cell 16 degree end cell end table end style

Perhatikan begin mathsize 14px style triangle ABC end style. Jumlah sudut dalam segitiga adalah begin mathsize 14px style 180 degree end style  dan begin mathsize 14px style y equals 16 degree end style sehingga dapat diperoleh:

begin mathsize 14px style table attributes columnalign right center left columnspacing 2px end attributes row cell straight m angle CAB plus straight m angle CBA plus straight m angle BAC end cell equals cell 180 degree end cell row cell open parentheses 2 y plus 8 degree close parentheses plus open parentheses 2 x plus 2 y close parentheses plus open parentheses 2 x plus 18 degree close parentheses end cell equals cell 180 degree end cell row cell open parentheses 2 times 16 degree plus 8 degree close parentheses plus open parentheses 2 x plus 2 times 16 degree close parentheses plus open parentheses 2 x plus 18 degree close parentheses end cell equals cell 180 degree end cell row cell 40 degree plus 2 x plus 32 degree plus 2 x plus 18 degree end cell equals cell 180 degree end cell row cell 90 degree plus 4 x end cell equals cell 180 degree end cell row cell 4 x end cell equals cell 180 degree minus 90 degree end cell row x equals cell fraction numerator 90 degree over denominator 4 end fraction end cell row x equals cell 22 comma 5 degree end cell end table end style

Karena begin mathsize 14px style y equals 16 degree end style dan begin mathsize 14px style x equals 22 comma 5 degree end style sehingga dapat diperoleh:

begin mathsize 14px style table attributes columnalign right center left columnspacing 2px end attributes row cell straight m angle CAB end cell equals cell 2 x plus 2 y end cell row blank equals cell 2 times 16 degree plus 2 times 22 comma 5 degree end cell row blank equals cell 32 plus 45 end cell row blank equals cell 77 degree end cell end table end style

Jadi, jawaban yang tepat adalah D.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 15 Maret 2021

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