Given:
Center of the circle = P
Let's determine the following:
a) Radius.
Here, the radius of the circle is the hypotenuse of the triangle.
Therefore, the radius of the circle is   3  units 
b) Center:
To find the point at the center of the circle, let's locate the point P on the graph.
On the graph, the point P is at (x, y) ==> (9, 4)
Therefore, the center (h, k) is   (9, 4) 
c) Value of a:
To find the value of a, let's first find the value of b.
Value of b = 6 - 4 = 2
Apply Pythagorean Theorem to find the value of a:
[tex]c^2=a^2+b^2[/tex]
Where:
c is the hypotenuse = 3
b = 2
Thus, we have:
[tex]\begin{gathered} 3^2=a^2+2^2 \\  \\ 9=a^2+4 \\  \\ \text{Subtract 4 from both sides:} \\ 9-4=a^2+4-4 \\  \\ 5=a^2 \\  \\ \text{Take the square root of both sides:} \\ \sqrt[]{5}=\sqrt[]{a^2} \\  \\ 2.2=a \\  \\ a=2.2 \end{gathered}[/tex]
Therefore, the value of a is  2.2  units
d) Value of b.
The value of b is   2 units 
ANSWERS:
• Radius: ,  3  units 
,
• Center: ,  (9, 4)  
,
• Value of a =   ,  2.2  units
,
• Value of b = ,  2 units