Jawab:
(1.) ≈ 31 ³/₇ cm²
(2.) = 12 cm
(3.) = 120 °

Penjelasan dengan langkah-langkah:

Rumus juring
L = (θ×π×r²)÷360
r = √((360×L)÷(θ×π))
θ = (360×L)÷(π×r²)
keterangan:
→ L = luas juring (cm²)
→ θ = sudut pusat ( ° )
→ r = jari-jari (cm)
→ π ≈ ²²/₇ atau 3,14
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(1.) Diketahui:
θ = 100 °
r = 6 cm
π ≈ ²²/₇
Ditanya L
L = (θ×π×r²)÷360
L ≈ (100ײ²/₇×6²)÷360
L ≈ (10ײ²/₇×36)÷36
L ≈ 10ײ²/₇
L ≈ ²²⁰/₇
L ≈ ²¹⁷/₇ + ³/₇
L ≈ 31 + ³/₇
L ≈ 31 ³/₇ cm²
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(2.) Diketahui:
θ = 25 °
L ≈ 31,4 cm²
π ≈ 3,14
Ditanya r
r = √((360×L)÷(θ×π))
r = √((360×31,4)÷(25×3,14))
r = √(11.304÷78,5)
r = √144
r = 12 cm
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(3.) Diketahui:
r = 90 cm
L ≈ 8.478 cm²
π ≈ 3,14
Ditanya θ
θ = (360×L)÷(π×r²)
θ = (360×8.478)÷(3,14×90²)
θ = (360×8.478)÷(3,14×8.100)
θ = 3.052.080÷25.434
θ = 120 °

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