How many square feet of outdoor carpet will we need for this hole?
1 answer:
Answer:
The area of the outdoor carpet = 60 - 6 - 6 = 48 ft²
Step-by-step explanation:
The picture below is what you are referring to .
The whole area of the shape forms a rectangle. A triangle and a rectangle has been cut off from the whole carpet rectangle. The square ft or area of the carpet is the subtraction of the area of the rectangle and triangle cut off from the whole area of the rectangle .
Area of the rectangle = Lb
where
L = 12 ft
b = 5 ft
area = 12 × 5 = 60 ft²
The cut off triangle area
area = 1/2 × base × height
area = 1/2 × 4 × 3
area = 12/2 = 6 ft²
The cut off rectangle area
area = Lb
area = 3 × 2
area = 6 ft²
The area of the outdoor carpet = 60 - 6 - 6 = 48 ft²
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9514 1404 393
Answer:
about 44.5 feet
Step-by-step explanation:
We can write relations for the height of the rail as a function of initial length and expanded length, but the solution cannot be found algebraically. A graphical solution or iterative solution is possible.
Referring to the figure in the second attachment, we can write a relation between the angle value α and the height of the circular arc as ...
h = c·tan(α) . . . . . . where c = half the initial rail length
Then the length of the expanded rail is ...
s = r(2α) = (c/sin(2α)(2α) . . . . . . where s = half the expanded rail length
Rearranging this last equation, we have ...
sin(2α)/(2α) = c/s
It is this equation that must be solved iteratively. We find the solution to be ...
α ≈ 0.0168538794049 radians
So, the height of the circular arc is ...
h = 2640.5·tan(0.0168538794049) ≈ 44.4984550191 . . . feet
The rail will bow upward by about 44.5 feet.
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<em>Additional comments</em>
Note that s and c in the diagram are half the lengths of the arc and the chord, respectively. The ratio of half-lengths is the same as the ratio of full lengths: c/s = 2640/2640.5 = 5280/5281.
We don't know the precise shape the arc will take, but we suspect is is not a circular arc. It seems likely to be a catenary, or something similar.
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We used Newton's method iteration to refine the estimate of the angle from that shown on the graph. The iterator used is x' = x -f(x)/f'(x), where x' is the next guess based on the previous guess of x. Only a few iterations are required obtain an angle value to full calculator precision.
