Answer: the shaded region = 69.66mm^2
Explanation:
Assume shaded region is X
Then :
X + Area of circle = area of square
X = area of square - area of circle
Find area of square:
Side length = 18mm
Area = 18 x 18 = 324
Find area of circle:
Side length of a square = the diameter of the circle = 18mm
And r(radius) = d/2 = 18/2 = 9
Area = pi x 9^2 = 254.34
Now find X
X = 324 - 254.34 = 69.66
Using the given data you can build the linear regression (described by linear function y=ax+b) by hand or you can use math calculator to do this. In attached diagram you can see that

and

Then the equation of linear function is

Answer: correct choice is D.
3.5555555556 / the third one
Formula for Perimeter of Rectangle:
P = 2(L + W)
Plug in 160:
160 = 2(L + W)
L = 4W
<span>So we can plug in '4W' for 'L' in the first equation.</span>
<span>160 = 2(L + W)
160 = 2(4W + W)
Combine like terms:
160 = 2(5W)
160 = 10W
Divide 10 to both sides:
W = 16
Now we can plug this back into any of the two equations to find the length.
L = 4W
L = 4(16)
L = 64
So the width is 16, and the length is 64.</span>