tolong di bantu beserta caranya

Mapel : MATEMATIKA
Materi : Lingkaran - Sudut, Juring, Busur

Diketahui :
Sudut (θ) = 120°
Panjang Busur = 36 cm

Ditanya : 
Keliling Lingkaran (K) = ?

Jawab :
K = 2 × π × r

[tex]Panjang\ Busur = \frac{\theta}{360}\times (2\times \pi \times r) \\ \\ 36 = \frac{120}{360}\times K \\ \\36 = \frac{1}{3}\times K \\ \\ K = 36\times 3 \\ \\ K=108\ cm........\text{Jawaban (D)}[/tex]

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