Answer:
The width of the field is 65 feet.
The length of the field is 780 feet.
A proper subset describes the set in full. An improper subset strays from the original set.
Answer: 20
Step-by-step explanation:
Split up the interval [0, 2] into <em>n</em> equally spaced subintervals:
![\left[0,\dfrac2n\right],\left[\dfrac2n,\dfrac4n\right],\left[\dfrac4n,\dfrac6n\right],\ldots,\left[\dfrac{2(n-1)}n,2\right]](https://tex.z-dn.net/?f=%5Cleft%5B0%2C%5Cdfrac2n%5Cright%5D%2C%5Cleft%5B%5Cdfrac2n%2C%5Cdfrac4n%5Cright%5D%2C%5Cleft%5B%5Cdfrac4n%2C%5Cdfrac6n%5Cright%5D%2C%5Cldots%2C%5Cleft%5B%5Cdfrac%7B2%28n-1%29%7Dn%2C2%5Cright%5D)
Let's use the right endpoints as our sampling points; they are given by the arithmetic sequence,

where
. Each interval has length
.
At these sampling points, the function takes on values of

We approximate the integral with the Riemann sum:

Recall that

so that the sum reduces to

Take the limit as <em>n</em> approaches infinity, and the Riemann sum converges to the value of the integral:

Just to check:

Length (L): 2w + 6
width (w): w
Perimeter (P) = 2L + 2w
240 = 2(2w + 6) + 2(w)
240 = 4w + 12 + 2w
240 = 6w + 12
228 = 6w
38 = w
Length (L): 2w + 6 = 2(38) + 6 = 76 + 6 = 82
Answer: width = 38 ft, length = 82 ft