Answer:
To solve for r, we can start by simplifying the equation:
1475/2pi = (3/4r^2pi) + (1/4pi*(r-15)^2) + (1/4pi(r-25)^2)
Multiplying both sides by 2*pi:
1475 = 3/4r^2pi2 + 1/4pi*(r-15)^22 + 1/4pi*(r-25)^2*2
1475 = 3/2r^2pi + 1/2pi(r-15)^2 + 1/2pi(r-25)^2
Multiplying both sides by 2:
2950 = 3r^2pi + pi*(r-15)^2 + pi*(r-25)^2
Distributing pi:
2950 = 3r^2pi + pir^2 - 30pir + 225pi + pir^2 - 50pir + 625pi
Combining like terms:
2950 = 5r^2pi - 80pir + 850*pi
Rearranging:
5r^2pi - 80pir + 850*pi - 2950 = 0
Simplifying:
5r^2pi - 80pir + 675*pi = 0
Dividing both sides by 5*pi:
r^2 - 16*r + 135 = 0
This is a quadratic equation, which can be solved using the quadratic formula:
r = (-(-16) ± sqrt((-16)^2 - 4(1)(135))) / (2(1))
r = (16 ± sqrt(256 - 540)) / 2
r = (16 ± sqrt(284)) / 2
r ≈ 1.7321 * 16 or r ≈ 8.2679
Since r represents the distance from the center of the octagon to a vertex, only the larger value of r makes sense in this context.
Therefore, r ≈ 8.2679 feet.
To find the area of the region in which the cow can graze, we can divide the octagon into eight congruent isosceles triangles with base 25 feet and height equal to the distance from the center to a side (which is equal to r).
The area of each triangle is (1/2)bh = (1/2)(25)(8.2679) = 103.3494 square feet.
Multiplying by 8 to account for all eight triangles:
8 * 103.3494 = 826.7952 square feet.
Rounding to the nearest square foot:
The area in which the cow can graze is approximately 827 square feet