First, a scale factor is the ratio of the corresponding sides in two similar geometric figures.
To find the scale factor:
1. Locate two corresponding sides (one on each figure).
2. Write the ratio of one length to the other.
And there you go! That's the scale figure from one figure to the other
Hope that helps and correct me if I'm wrong!
I think that the answer would be D
You have to look for -3 on the x axis, and then proceed vertically (in this case upwards) until you meet the graph.
We land about 1/2 square above the 12 mark on the y axis. Since one square is 1/2 unit, a half square would be 1/4 unit.
So, we can estimate 
Answer:
a)
b) (a,b) (c, d) As long as (a,b) and (c,d) are the endpoints of of the diameter.
Step-by-step explanation:
a)
1) The reduced formula of the Circumference is given by:

2) Let's expand the factored one into one closer to the pattern above:

3) Completing the square for both trinomials:

4) In the Reduced Formula,
,

b) Using the previous example to show this:
When we factor this way

We are indeed, naming "a" and "b", the coordinates of (a, b) of the first endpoint and "b" and "d" the second endpoint as well.Id est, D (2, 5) and B (6,-11).
The radius, is 
So yes, the equation of the circle can be written as

As long as (a,b) and (c,d) are the endpoints of of the diameter.

Step-by-step explanation:
A(promotional sign)b
A=kb
4=21k
K=0. 1904
A=0. 2b
A=0. 2×7
A=1. 4