Math Problem Statement

Find in each case whether the given point lies inside, outside or on the given circle. (−4, 1) , x^2 + y^2 + 2x + 8y − 13 = 0

Solution

To determine whether the given point (4,1)(-4, 1) lies inside, outside, or on the circle defined by the equation x2+y2+2x+8y13=0x^2 + y^2 + 2x + 8y - 13 = 0, we need to compare the point's distance from the circle's center with the circle's radius.

Step 1: Rewrite the Circle's Equation in Standard Form

The equation of the circle is given as: x2+y2+2x+8y13=0x^2 + y^2 + 2x + 8y - 13 = 0

We will complete the square for both xx and yy terms:

  1. For the xx terms: x2+2xx^2 + 2x

    • Add and subtract (22)2=1\left(\frac{2}{2}\right)^2 = 1, so it becomes (x+1)21(x + 1)^2 - 1.
  2. For the yy terms: y2+8yy^2 + 8y

    • Add and subtract (82)2=16\left(\frac{8}{2}\right)^2 = 16, so it becomes (y+4)216(y + 4)^2 - 16.

Substituting these back into the equation: (x+1)21+(y+4)21613=0(x + 1)^2 - 1 + (y + 4)^2 - 16 - 13 = 0

Simplify the equation: [ (x + 1)^2 + (y + 4)^2 - 30 = 0