Monoxdifly
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The center of circle L is located in the first quadrant and lays on the line y = 2x. If the circle L touches the Y-axis at (0,6), the equation of circle L is ...
a. $$x^2+y^2-3x-6y=0$$
b. $$x^2+y^2-12x-6y=0$$
c. $$x^2+y^2+6x+12y-108=0$$
d. $$x^2+y^2+12x+6y-72=0$$
e. $$x^2+y^2-6x-12y+36=0$$
Since the center (a, b) lays in the line y = 2x then b = 2a.
$$(x-a)^2+(y-b)^2=r^2$$
$$(0-a)^2+(6-b)^2=r^2$$
$$(-a)^2+(6-2a)^2=r^2$$
$$a^2+36-24a+4a^2=r^2$$
$$5a^2-24a+36=r^2$$
What should I do after this?
a. $$x^2+y^2-3x-6y=0$$
b. $$x^2+y^2-12x-6y=0$$
c. $$x^2+y^2+6x+12y-108=0$$
d. $$x^2+y^2+12x+6y-72=0$$
e. $$x^2+y^2-6x-12y+36=0$$
Since the center (a, b) lays in the line y = 2x then b = 2a.
$$(x-a)^2+(y-b)^2=r^2$$
$$(0-a)^2+(6-b)^2=r^2$$
$$(-a)^2+(6-2a)^2=r^2$$
$$a^2+36-24a+4a^2=r^2$$
$$5a^2-24a+36=r^2$$
What should I do after this?