Answer:
8. 504ft²
9. 4970yd² (rounded to 3 s.f.)
Formulas (For easy reference):
Area of rectangle = length × breadth
Area of circle = pi×r×r
Circumference of circle = pi×r×2
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Explanation:
8. You know a box has 6 sides, and there are 3 types of surfaces that are different from each other, and you have to multiply each side by 2 cus there are the front and backside (You can draw the box with its dimensions to see the 3 types of surfaces and why I multiplied by 2):
(2×12×6) + (2×12×10) + (2×6×10) = 144 + 240 + 120
= 504ft²
9. The net of a cylinder contains two circles of radius 24yd and one long sheet to wrap around the circles with the length that is the circumference of the circle (so that it can wrap around the two circles) and a width which is the height of the cylinder (9yd).
2 Circles = 2×pi×24×24
= 1152pi
Long sheet = 9×24×2×pi
= 432pi
Now we can add all of them together:
432pi+1152pi = 1584pi
= 4970yd² (rounded to 3 s.f.)