tolong bantu ya, besok dikumpulin:D

[tex]1) \: \frac{50}{360} \times 2\pi \times r = 40..... > r = \frac{40 \times 36}{10\pi} = \frac{144}{\pi} \\ maka \: panjang \: busur \: ac = \\ \frac{180 - (30 + 50)}{360} \times 2\pi \times \frac{144}{\pi} = \frac{100}{360} \times 288 = 80 \: cm \\ panjang \: busur \: ad = \\ \frac{130}{360} \times 2\pi \times \frac{144}{\pi} = \frac{288 \times 13}{36} = 104[/tex]
[tex]2) \: \: \frac{120}{360} \times \pi \times {r}^{2} = 45... > {r}^{2} = \frac{45 \times 3}{\pi} \\ luas \: juring \: opqr = \\ \frac{90 + 120}{360} \times \pi \times \frac{45 \times 3}{\pi} = \frac{21 \times 45 \times 3}{36} = 78.75 \: {cm}^{2} \\ luas \: juring \: opr = (45 \times 3) - 78.75 = 56.25 \: {cm}^{2} [/tex]