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\section*{Juring, Tembereng, dan Apotema Lingkaran}

\subsection*{Juring: potongan yang titiknya di pusat}
Lingkaran berjari-jari 3 cm, sudut pusat $60^\circ$. Luas juring $= \frac{60}{360} \times \pi \times 3^2 = 1{,}5\pi \approx 4{,}71$ cm$^2$.
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\subsection*{Tembereng: daerah antara tali busur dan busur}
Lingkaran berjari-jari 3 cm, sudut pusat $120^\circ$. Luas tembereng $\approx 3\pi - 3{,}90 \approx 5{,}52$ cm$^2$.
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\subsection*{Apotema: garis tegak lurus dari pusat ke tali busur}
Lingkaran berjari-jari 5 cm, tali busur 8 cm, apotema $= \sqrt{5^2 - 4^2} = 3$ cm.
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