The general formula for the distance between two points is

Anyway, if A and B have the same x or y coordinates, this formula can be simplified. For example, in this case the two points have the same x coordinate of -8, so the following part of the formula simplifies:

So, we're left with

but the square root of a square is the absolute value of the object being squared:

which is this case means 
which is the correct length of the side.
Answer:
24
Step-by-step explanation:
area = wl (6×4 = 24)
w width l length
Answer:
Cost function = 40a + 500
Cost of 90 articles = $4,100
Step-by-step explanation:
The fixed cost is $500 and it will.not change regardless of production level.
The Variable cost is $40 and increases by every additional unit produced.
Assume the number of articles produced is a.
Cost function would be:
Total cost = Variable cost * Number of articles + Fixed cost
TC = 40a + 500
Using this, the cost of 90 articles is:
= 40 * 90 + 500
= $4,100