Pertanyaan

cos 105° – cos 15° = ...

D. Kamilia

Master Teacher

Mahasiswa/Alumni Universitas Negeri Malang

Jawaban terverifikasi

Pembahasan

Ingat bahwa : Sehingga :

Ingat bahwa :

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

Sehingga :

$begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell cos invisible function application 105 degree minus cos invisible function application 15 degree end cell equals cell negative 2 sin invisible function application left parenthesis fraction numerator 105 degree plus 15 degree over denominator 2 end fraction right parenthesis space sin invisible function application left parenthesis fraction numerator 105 degree minus 15 degree over denominator 2 end fraction right parenthesis space end cell row blank equals cell negative 2 space sin invisible function application left parenthesis fraction numerator 120 degree over denominator 2 end fraction right parenthesis space sin invisible function application left parenthesis fraction numerator 90 degree over denominator 2 end fraction right parenthesis space end cell row blank equals cell negative 2 space sin invisible function application 60 degree space sin invisible function application 45 degree space end cell row blank equals cell negative 2 left parenthesis 1 half square root of 3 right parenthesis left parenthesis 1 half square root of 2 right parenthesis end cell row blank equals cell negative 1 half square root of 6 end cell end table end style$