11. Circumference equals pi times diameter. To find the diameter, divide the circumference (40074) by 3.14.
Final answer: (approximately) 12762 km
12. Area of a circle equals radius squared times [tex] \pi [/tex]. Square the radius (21) to get 441. Plug this into the equation. It should look like this:
441 x 22/7 = 1386
Final answer:1386 square meters
13. Let's find the area of the rectangle first which is base(10) times height (18). The area should be 180. Now let's find the area of the semicircle. The area of a circle is radius squared times [tex] \pi [/tex], so we can solve for the circle and divide by 2 to find the area of the semi circle. The diameter they gave us is 18, so divide that by 2 to get the radius which is 9. Square 9, which is 81 and multiply that by 3.14. The area of the circle should be 254.34. Divide by 2 to get 127.17. Add that to 180 to get 307.71
Final answer: (approximately) 307 [tex] cm^{2} [/tex]
