Because angle B is the largest angle. AC is the largest side.
In a triangle, the largest angle opposes the largest side.
The answer to this question would be: 750ft
In this question, you are given the rectangle perimeter (2,000 ft) and the ratio of rectangle length:width (3:1). The equation of this question should be:
3*rectangle width = 1 *rectangle length
rectangle width = 1/3 rectangle length
rectangle perimeter = 2,000ft
Then using the rectangle formula, you will be able to find the length. It would be:
rectangle perimeter = 2* (length+width)
2,000ft /2 = 1/3 length + length
1 1/3 length= 1,000ft
length = 1,000ft /4 *3= 750ft