Answer to Question #260085 in Geometry for Carmen

Question

Given that P is a point on the circle x^2 +y^2 - 4x +2y - 4=0. Find the longest distance from P to the y-axis.

Answer 1

(x-a) ² + (y-b) ²=r²

(a, b) is the center of the circle

X²+y²-4x+2y-4=0

X²-4x+(-4/2)²+y²+2y+(2/2)²=4+(-4/2)²+(2/2)²

(x-2)2+(y+1)2=9

-a=-2

a=2

-b=1

b=-1

r²=9

r=3

The longest Distance =3+2=5

Ans=5units