It's about TRIGONOMETRY...need some help?

Question

1.)A rectangular garden is to be fenced off with 100ft. of fencing material.

a.) Let x feet be the length of the garden; express the number of square feet in the area of the garden as a function of x

b.) What is the Domain of the resulting function?

Answer 1

length = x
width = y
perimeter = 2x + 2y = 100
100 - 2x = 2y
y = 50 - x

Area = xy = x(50 - x) = 50x - x^2

Domain: 0 < x < 50

Answer 2

If the available fencing is 100 feet long, and the lot is rectangular, it will take 50 feet of fence in total to go halfway around the garden. Set the dimension variables as follows:

Width: x
Length: 50 - x

Area = width*length = 50x - x²


Domain of the function: 0

Answer 3

Question a)
Let length = x and breadth = b
100 = 2x + 2b
2b = 100 - 2x
b = 50 - x
A(x) = x (50 - x)

Question b)
Domain is { x : 0 < x < 50 }