Posted by **alk** on Friday, July 18, 2008 at 1:03pm.

For the circle x^2+y^2+6x-4y+3=0

how would i go about finding:

a) the center and the radius

b) the equation of the tangent line at the point (-2,5)

any help is mch appreciated. thanks!

- math -
**drwls**, Friday, July 18, 2008 at 3:20pm
(a) Rewrite the equation as

x^2 + 6x + 9 + y^2 -4y + 4 +3 -13 = 0

(x+3)^2 + (y-2)^2 = 10 = (sqrt 10)^2

The should tell you that the center is at (-3, 2) and the circle radius is sqrt 10.

(b) First cmpute the slope dy/dx at (-2, 5)using implicit differentiation.

2x + 2y y' + 6 -4 y'= 0

y'(4 - 2y) = 2x + 6

y' = 2/(4-2y) = -1/3

Finally, write down the equation of s straight line passing through (-2,5) with that slope.

Verify my numbers. I may have goofed somewhere along the line

## Answer this Question

## Related Questions

- calc - standard equation of circle concentric with X^2+Y^2-2X-8Y+1=0 and tangent...
- Math (Pre Cal) - Hi, I am studying for a precalculus quiz and I do not ...
- math - a circle is tangent to the y-axis at y=3 and has one x-intercept at x=1 a...
- Please Help! Math - How to find the center and radius of a circle using 3 points...
- math - From an exteror point P that is h units form a circle of radius r, a ...
- MATH - How do i find the center of a circle using 3 points. Also need to find ...
- Math (geometry) - Line l is tangent to circle O at point P(3,4) where the center...
- Math - I have a series of questions that I did. They lead up to the last ...
- Math - I have a question my brother asked me but I need a math expert. You have ...
- Alg2 - The tangent to a circle may be defined as the line that intersects the ...