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Pada segitiga ABC diketahui 3 sin A + 4 cos B = 6 dan 3 cos A + 4 sin B = 1. Nilai sin C adalah...

Pada segitiga ABC diketahui 3 sin A + 4 cos B = 6 dan 3 cos A + 4 sin B = 1. Nilai sin C adalah...

  1. begin mathsize 12px style 1 half end style

  2. begin mathsize 12px style 1 half square root of 2 end style

  3. begin mathsize 12px style 1 half square root of 3 end style

  4. begin mathsize 12px style square root of 3 end style

  5. 1

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A. Acfreelance

Master Teacher

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Misal: 3 sin A + 4 cos B = 6 ... (1) 3 cos A + 4 sin B = 1 ... (2) Persamaan (1) dan (2) di kuadratkan lalu di jumlahkan, maka: Ingat! maka Sudut dalam segitiga ABC, maka C = Sehingga, nilai dari sin C yaitu:

Misal:

3 sin A + 4 cos B = 6 ... (1)

3 cos A + 4 sin B = 1 ... (2)

Persamaan (1) dan (2) di kuadratkan lalu di jumlahkan, maka:

begin mathsize 12px style open parentheses 3 space sin space A plus 4 space cos space B equals 6 close parentheses squared left right arrow 9 space sin squared space A plus 16 space cos squared space B plus 24 space sin space A space cos space B equals 36  open parentheses 3 space cos space A plus 4 space sin space B equals 1 close parentheses squared left right arrow 9 space cos squared space A plus 16 space sin squared space B plus 24 space cos space A space sin space B equals 1    9 space sin squared space A plus 16 space cos squared space B plus 24 space sin space A space cos space B equals 36  bottom enclose 9 space cos squared space A plus 16 space sin squared space B plus 24 space cos space A space sin space B equals space space 1 end enclose space space plus  9 open parentheses sin to the power of 2 space end exponent A plus cos squared space A close parentheses plus 16 open parentheses sin squared space B plus cos squared space B close parentheses plus 24 open parentheses sin space A space cos space B plus cos space A space sin space B close parentheses equals 37 end style

 

Ingat!

begin mathsize 12px style sin squared space A plus cos squared space A equals 1  sin open parentheses A plus B close parentheses equals sin space A space cos space B plus cos space A space sin space B  sin open parentheses A minus B close parentheses equals sin space A space cos space B minus cos space A space sin space B end style

maka

size 12px 9 open parentheses size 12px sin to the power of size 12px 2 size 12px space end exponent size 12px A size 12px plus size 12px cos to the power of size 12px 2 size 12px space size 12px A close parentheses size 12px plus size 12px 16 open parentheses size 12px sin to the power of size 12px 2 size 12px space size 12px B size 12px plus size 12px cos to the power of size 12px 2 size 12px space size 12px B close parentheses size 12px plus size 12px 24 open parentheses size 12px sin size 12px space size 12px A size 12px space size 12px cos size 12px space size 12px B size 12px plus size 12px cos size 12px space size 12px A size 12px space size 12px sin size 12px space size 12px B close parentheses size 12px equals size 12px 37  size 12px 9 size 12px. size 12px 1 size 12px plus size 12px 16 size 12px. size 12px 1 size 12px plus size 12px 24 open parentheses size 12px sin open parentheses size 12px A size 12px plus size 12px B close parentheses close parentheses size 12px equals size 12px 37  size 12px 24 open parentheses size 12px sin open parentheses size 12px A size 12px plus size 12px B close parentheses close parentheses size 12px equals size 12px 12  size 12px sin open parentheses size 12px A size 12px plus size 12px B close parentheses size 12px equals size 12px 1 over size 12px 2

 

Sudut dalam segitiga ABC, maka C = begin mathsize 12px style 180 degree minus open parentheses A plus B close parentheses end style

Sehingga, nilai dari sin C yaitu:

begin mathsize 12px style sin space C equals sin open parentheses 180 degree minus open parentheses A plus B close parentheses close parentheses  sin space C equals sin space 180 degree space cos open parentheses A plus B close parentheses minus cos space 180 degree space sin open parentheses A plus B close parentheses  sin space C equals sin open parentheses A plus B close parentheses  sin space C equals 1 half end style

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