Pertanyaan

cos 105° + cos 15° = ....

D. Kamilia

Master Teacher

Mahasiswa/Alumni Universitas Negeri Malang

Jawaban terverifikasi

Pembahasan

Ingat bahwa : Sehingga :

Ingat bahwa :

$begin mathsize 14px style cos invisible function application straight alpha plus cos invisible function application straight beta equals 2 space cos invisible function application open parentheses fraction numerator straight alpha plus straight beta over denominator 2 end fraction close parentheses space cos invisible function application open parentheses fraction numerator straight alpha minus straight beta over denominator 2 end fraction close parentheses end style$

Sehingga :

$begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell cos invisible function application 105 degree plus cos invisible function application 15 degree end cell equals cell 2 space cos invisible function application open parentheses fraction numerator 105 degree plus 15 degree over denominator 2 end fraction close parentheses space cos invisible function application open parentheses fraction numerator 105 degree minus 15 degree over denominator 2 end fraction close parentheses space end cell row blank equals cell 2 space cos invisible function application open parentheses fraction numerator 120 degree over denominator 2 end fraction close parentheses space cos invisible function application open parentheses fraction numerator 90 degree over denominator 2 end fraction close parentheses space end cell row blank equals cell 2 space cos invisible function application 60 degree space cos invisible function application 45 degree space end cell row blank equals cell 2 open parentheses 1 half close parentheses open parentheses 1 half square root of 2 close parentheses end cell row blank equals cell 1 half square root of 2 end cell end table end style$