equation of circles: Center (3, -2); Soln point (-1,1), etc

[Guest]

For these 2 problems, we are to find the standard form of the equation of the specified circle.
I'm not positive on how to do these problems, so this is how I went about them:

1) Center: (3, -2); Solution point: (-1,1)
R= (sqrt(3+1)^2 +(-2-1)^2)
= (sqrt(4)^2 + (-3)^2)
=(sqrt(16+9))
=sqrt 25
= 5
(x-3)^2 +(y+2)^2 = 5^2
= (x-3)^2 +(y+2)^2 = 25


2) Enpoints of a diameter: (-4, -1), (4, 1)
Midpoint: (-4+4)/2 , (-1+1)/2 = (0, 0)
(x-0)^2 +(y-0)^2=2R
2r= (sqrt(2x_2-2x_1)^2 + (2y_2-2y_1)^2)
= (Sqrt(-8-8)^2 +(-2-2)^2)
= (sqrt(-16^2 + -4^2))
= (sqrt(256+16))
=sqrt 272 = 16.49 * 2 = 33
x^2+y^2 = 33

 

[stapel]

In the future, please post replies to the original thread, rather than to new, disconnected threads.

Thank you.

Eliz.