Answer:
<em>The coordinates of P are (-2,0)</em>
<em>The radius of the circle is 5.</em>
Step-by-step explanation:
<u>Analytic geometry</u>
The diagram shows a circle with center P, and two points A(-6,3) and B(2,-3) that form the diameter of the circle.
a)
The center of the circle lies at the midpoint of A and B. The midpoint (xm,ym) can be calculated by:
![\displaystyle x_m=\frac{x_1+x_2}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x_m%3D%5Cfrac%7Bx_1%2Bx_2%7D%7B2%7D)
![\displaystyle y_m=\frac{y_1+y_2}{2}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20y_m%3D%5Cfrac%7By_1%2By_2%7D%7B2%7D)
Substituting x1=-6, x2=2, y1=3, y2=-3:
![\displaystyle x_m=\frac{-6+2}{2}=\frac{-4}{2}=-2](https://tex.z-dn.net/?f=%5Cdisplaystyle%20x_m%3D%5Cfrac%7B-6%2B2%7D%7B2%7D%3D%5Cfrac%7B-4%7D%7B2%7D%3D-2)
![\displaystyle y_m=\frac{3-3}{2}=0](https://tex.z-dn.net/?f=%5Cdisplaystyle%20y_m%3D%5Cfrac%7B3-3%7D%7B2%7D%3D0)
Thus, the coordinates of P are (-2,0)
b) The radius of the circle is the distance from the center to any point in its circumference. We can use the distance from P to A or B indistinctly.
Given two points A(x1,y1) and P(x2,y2), the distance between them is:
![d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}](https://tex.z-dn.net/?f=d%3D%5Csqrt%7B%28x_2-x_1%29%5E2%2B%28y_2-y_1%29%5E2%7D)
Substituting x1=-6, x2=-2, y1=3, y2=0:
![r=\sqrt{(-2+6)^2+(0-3)^2}](https://tex.z-dn.net/?f=r%3D%5Csqrt%7B%28-2%2B6%29%5E2%2B%280-3%29%5E2%7D)
![r=\sqrt{4^2+(-3)^2}](https://tex.z-dn.net/?f=r%3D%5Csqrt%7B4%5E2%2B%28-3%29%5E2%7D)
![r=\sqrt{16+9}=\sqrt{25}=5](https://tex.z-dn.net/?f=r%3D%5Csqrt%7B16%2B9%7D%3D%5Csqrt%7B25%7D%3D5)
The radius of the circle is 5.