Pertanyaan

Bila sin ( 4 0 ∘ + x ) = α , 0 ∘ < x < 4 5 ∘ maka cos ( 7 0 ∘ + x ) = ...

Bila $sin (4 0^{\circ} + x) = α, 0^{\circ} < x < 4 5^{\circ}$ maka $cos (7 0^{\circ} + x) = ...$

$fraction numerator square root of 1 minus alpha squared end root minus alpha over denominator 2 end fraction$
$fraction numerator square root of 3 open parentheses 1 minus alpha squared close parentheses end root minus alpha over denominator 2 end fraction$
$fraction numerator square root of 3 open parentheses 1 minus alpha squared close parentheses end root plus alpha over denominator 2 end fraction$
$fraction numerator square root of 2 open parentheses 1 minus alpha squared close parentheses end root plus alpha over denominator 2 end fraction$
$fraction numerator square root of 2 open parentheses 1 minus alpha squared close parentheses end root minus alpha over denominator 2 end fraction$

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Habis dalam

Klaim

I. Roy

Master Teacher

Mahasiswa/Alumni Universitas Negeri Surabaya

Jawaban terverifikasi

Pembahasan

Penyelesaian : Diketahui : maka: Ingat! Penjumlahan cosinus sudut: cos (A + B) = cos A.cos B – sin A.sin B Sehingga:

Penyelesaian :

Diketahui :

maka:

Ingat!

Penjumlahan cosinus sudut:

cos (A + B) = cos A.cos B – sin A.sin B

Sehingga:

$cos space open parentheses 70 degree plus x close parentheses equals cos space open parentheses open parentheses 40 degree plus x close parentheses plus 30 degree close parentheses equals cos space open parentheses 40 degree plus x close parentheses. cos space 30 degree minus sin space open parentheses 40 degree plus x close parentheses. sin space 30 degree equals open parentheses square root of 1 minus alpha squared end root close parentheses. open parentheses 1 half square root of 3 close parentheses minus open parentheses alpha close parentheses. open parentheses 1 half close parentheses equals 1 half open parentheses square root of 3 open parentheses 1 minus alpha squared close parentheses end root minus a close parentheses equals fraction numerator square root of 3 open parentheses 1 minus alpha squared close parentheses end root minus a over denominator 2 end fraction$