Tolong di bantu yhaa !!!please.... Question from @Anggita1423

May 2019 1 29 Report

$keliling = 2r \: r = \pi \: d \\ luas \: = n{r}^{2} = \frac{1}{4} \pi {d}^{2} \\ tentukan \: \\ 1. \: keliling \:lingkran \: dan \: luas \\ a. \: r = 70cm \: \pi \frac{22}{7} \\ b.r = 10cm \: \pi = 3.14 \\ c.diameter \: 21cm \: dengan \: \pi = \frac{22}{7} \\ d.diameter \: 15cm \: dengan \: \pi = 3.14 \\ 2.tentukan \: jari - jari \: lingkaran \: jika \: \\ a.keliling = 66cm \: \pi = \frac{22}{7} \\ b.keliling = 94.2cm \: \pi 3.14 \\ c.luas \: 154cm\pi \frac{22}{7} \\ d.luas \: 314cm\pi = 3.14$
Tolong di bantu yhaa !!!
please.

2precis3

Verified answer

No. 1A

$K = 2\pi r = 2 \cdot \frac{22}{7} \cdot 70\:\text{cm} = 440\:\text{cm} \\ \\
L = \pi r^2 = \frac{22}{7} \cdot 70\:\text{cm} \cdot 70\:\text{cm} = 15400\:\text{cm}^2 = 1.54\:\text{m}^2$

No. 1B

$K = 2\pi r = 2 \cdot 3.14 \cdot 10\:\text{cm} = 62.8\:\text{cm} \\ \\
L = \pi r^2 = 3.14 \cdot 10\:\text{cm} \cdot 10\:\text{cm} = 314\:\text{cm}^2$

No. 1C

$K = \pi d = \cdot \frac{22}{7} \cdot 21\:\text{cm} = 66\:\text{cm} \\ \\ 
L = \frac{1}{4} \pi d^2 = \frac{1}{4} \frac{22}{7} \cdot 21\:\text{cm} \cdot 21\:\text{cm} = 346.5\:\text{cm}^2$

No. 1D

$K = \pi d = 3.14 \cdot 15\:\text{cm} = 47.1\:\text{cm} \\ \\ L = \frac{1}{4} \pi d^2 = \frac{1}{4} \cdot 3.14 \cdot 15\:\text{cm} \cdot 15\:\text{cm} = 176.625\:\text{cm}^2$

No. 2A

$r = \frac{K}{2\pi} = \frac{66\:\text{cm}}{2\cdot(22/7)} = \frac{33\cdot7}{22}\:\text{cm} = 10.5\:\text{cm}$

No. 2B

$r = \frac{K}{2\pi} = \frac{94.2\:\text{cm}}{2\cdot3.14} = \frac{30}{2}\:\text{cm} = 15\:\text{cm}$

No. 2C

$r = \sqrt{\frac{L}{\pi}} = \sqrt{\frac{154\:\text{cm}^2}{22/7}}=\sqrt{49\:\text{cm}^2}=7\:\text{cm}$

No. 2D

$r = \sqrt{\frac{L}{\pi}} = \sqrt{\frac{314\:\text{cm}^2}{3.14}}=\sqrt{100\:\text{cm}^2}=10\:\text{cm}$

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