bantu jawab ya ini .....
Lp = 2 × phi × r × ( r + t )
Lp = 2 × 3,14 × 20cm × ( 20cm + 12cm )
Lp = 2 × 3,14 × 20cm × 32cm
Lp = 2 × 3,14 × 640cm
Lp = 2 × 2009,6cm
Lp = 4019,2cm²
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d = 40 cm
r = d : 2 = 20 cm
t = 12 cm
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Lp = 2 × Ο × r × (r + t)
= 2 × 3,14 × 20 × (20 + 12)
= 125,6 × 32
= 4.019,2 cm² ☑
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