Answer:
19 m
Step-by-step explanation:
Perimeter = 2(length + width) ; P = 2(l+w) - - (1)
Area = Length * width ; A = l*w - - - (2)
76 = 2(l+w)
76/2 = l+w
l+w = 38
l = 38 - w
Put l = 38 - w in (1)
A = (38-w)*w
A = 38w - w²
At maximum point:
dA/dw = 0
dA/dw = 38 - 2w
38 - 2w = 0
38 = 2w
w = 38/2
w = 19