Step-by-step explanation:
Let x be the length and y be the width of the rectangular plot.
The plot is bounded on one side by a river and on the other three sides by a single-strand electric fence. It means,
x+2y = 1500
x = 1500 - 2y ....(1)
We know that the area of a rectangular plot is given by :
A = xy ....(2)
Put the value of x from equation (1) in (2)
.....(3)
For largest area, differentiate above area equation wrt y.

Put the value of y in equation (1).
x = 1500-2(375)
= 750 m
Put the value of y in equation (3).

Hence, the largest area is 281250 m² and its dimensions are 750 m and 375 m.
The rate of change is -6 because it’s being subtracted by 6 each time.
Answer: Approximately d = 208.72
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Work Shown:
Make sure your calculator is in radian mode
A quick way to check is to compute cos(pi) and you should get -1
cos(angle) = adjacent/hypotenuse
cos(x) = 200/d
cos(0.29) = 200/d
d*cos(0.29) = 200
d = 200/cos(0.29)
d = 208.715135166392 which is approximate
d = 208.72
I rounded to two decimal places since x is rounded in that manner as well. Round however else you need if your teacher instructs.
13x - 4 < 12(x-1)
13x - 4 < 12x - 12
13x - 12x < -12 + 4
x < -8
x > 8
x is greater than 8