Answer:
x = 140 y = 105 x · y = 14700 m²
Step-by-step explanation:
good question
it looks like 3 sides of length x
and 4 sides of length y
area 1 = area 2
and the length of all the sides sum to 840
3x + 4y = 840 find the maximum area = 2· x · y
This is a calculus problem that I can't remember how solve
if x = 0 y = 210
if y = 0 x = 280 280 / 2 = 140 the mid-point the logical answer
if x = 140 y = 105 x · y = 14700 m² this appears to be the max
if x = 135 y = 108.75 x · y = 14681.25 m² smaller area
if x = 145 y = 101.25 x · y = 14681.25 m² smaller area
I need an eqaution with a quadratic and take the first derivative
y = (840 - 3x) / 4 xy = max area y = max area/x
(max area) / x = (840 - 3x) / 4 solve for x
max area = x(840 - 3x) / 4
max area = [840x/4 - 3x²/4] '
max area = 210x - 3x²/4 take the first derivative
max area = 210 - 6x/4 maximum occurs when slope = 0
0 = 210 - 3x/2
3x/2 = 210
x = 210·2/3
x = 420 / 3
x = 140 y = 105
3(140) + 4(105) = 420 + 420 = 840 checks
