The equation of a circle is x² + y²-6y+1=0. What are the coordinates of
the center and the length of the radius of this circle?
(1) center (0,3) and radius 2√2
(2) center (0,-3) and radius 2√2
(3) center (0.6) and radius √35
(4) center (0,-6) and radius √35

Respuesta :

Answer:

center (0, 3) and radius 2√2

Step-by-step explanation:

Equation of a circle

[tex](x-a)^2+(y-b)^2=r^2[/tex]

where:

  • (a, b) is the center
  • r is the radius

Given equation:

[tex]x^2+y^2-6y+1=0[/tex]

Subtract 1 from both sides:

[tex]\implies x^2+y^2-6y=-1[/tex]

To create a trinomial with variable y, add the square of half the coefficient of the y term to both sides:

[tex]\implies x^2+y^2-6y+\left(\dfrac{-6}{2}\right)^2=-1+\left(\dfrac{-6}{2}\right)^2[/tex]

[tex]\implies x^2+y^2-6y+9=8[/tex]

Factor the trinomial with variable y:

[tex]\implies x^2+(y^2-6y+9)=8[/tex]

[tex]\implies x^2+(y-3)^2=8[/tex]

Factor [tex]x^2[/tex] to match the general form for the equation of a circle:

[tex]\implies (x-0)^2+(y-3)^2=8[/tex]

Compare with the general form of the equation for a circle:

[tex]\implies a=0[/tex]

[tex]\implies b=3[/tex]

[tex]\implies r^2=8 \implies r=2\sqrt{2}{[/tex]

Therefore, the center is (0, 3) and the radius is 2√2