No.
A chord is a straight segment that joins two points of the circumference. It starts at a point in the circumference and ends at other point in the circumference.
The radius goes from the center of the circle (which is not on the circumference) to one point of the circumference.
The diameter is a chord (the largest chord possible); but not the radius.
        
                    
             
        
        
        
The answer is y = -7x
Expalnation
Two points on the table are (0,0) and (1,-7)
Change in y = -7-0 = -7
Change in x = 1-0 = 1
Slope m of the function = -7/1= -7
Using y= mx + c
Picking point (0,0), x = 0, y = 0
y = mx + c becomes 
0 = -7(0) + c
0 = 0 + c
c= 0
Hence, the equation is y = -7x + 0
which is y = -7x
Option b is the correct answer
 
        
             
        
        
        
Step-by-step explanation:

 
        
             
        
        
        
If you divide.40 into 9 you will get 22.5 which is your answer