Pertanyaan

Perhatikan gambar berikut. Panjang BC adalah ...

Perhatikan gambar berikut.

Panjang BC adalah ...

S. Ayu

Master Teacher

Mahasiswa/Alumni Universitas Muhammadiyah Prof. DR. Hamka

Jawaban terverifikasi

Pembahasan

Tentukan terlebih dahulu panjang sisi BD dengan aturan cosinus. Kemudian dengan menggunakan aturan cosinus kita dapatkan panjang BC. Maka, panajng BC adalah .

Tentukan terlebih dahulu panjang sisi BD dengan aturan cosinus.

$table attributes columnalign right center left columnspacing 0px end attributes row cell BC squared end cell equals cell AB squared plus AD squared minus 2 times AB times AD times cos space straight A end cell row cell BC squared end cell equals cell open parentheses 6 square root of 2 close parentheses squared plus 6 squared minus 2 times 6 square root of 2 times 6 times cos space 45 degree end cell row cell BC squared end cell equals cell 72 plus 36 minus 72 square root of 2 times fraction numerator square root of 2 over denominator 2 end fraction end cell row cell BC squared end cell equals cell 108 minus fraction numerator 72 times down diagonal strike 2 over denominator down diagonal strike 2 end fraction end cell row cell BC squared end cell equals cell 108 minus 72 end cell row cell BC squared end cell equals 36 row BC equals cell plus-or-minus square root of 36 end cell row BC equals cell plus-or-minus 6 end cell row BC equals cell 6 space cm end cell end table$

Kemudian dengan menggunakan aturan cosinus kita dapatkan panjang BC.

$table attributes columnalign right center left columnspacing 0px end attributes row cell BC squared end cell equals cell BD squared plus CD squared minus 2 times BD times CD times cos space straight D end cell row cell BC squared end cell equals cell 6 squared plus open parentheses 3 square root of 3 close parentheses squared minus 2 times 6 times 3 square root of 3 times cos space 30 degree end cell row cell BC squared end cell equals cell 36 plus 27 minus 36 square root of 3 times fraction numerator square root of 3 over denominator 2 end fraction end cell row cell BC squared end cell equals cell 63 minus fraction numerator 36 times 3 over denominator 2 end fraction end cell row cell BC squared end cell equals cell 63 minus 54 end cell row cell BC squared end cell equals 9 row BC equals cell plus-or-minus square root of 9 end cell row BC equals cell plus-or-minus 3 end cell row BC equals cell 3 space cm end cell end table$

Maka, panajng BC adalah 3 space cm .