Equation of Circle: Centre (2,-4), y-intercept 1

[veronika_bebs]

Homework Statement

find the equation of a circle with centre of (2,-4) and y-intercept 1

Homework Equations

The Attempt at a Solution

 

[n!kofeyn]

The equation of a circle of radius r centered at the point (a,b) is given by (x-a)²+(y-b)²=r². Since you already are given the point (a,b), all you need to find is the radius of the circle. Can you use the information that a y-intercept is (0,1) to find the radius?

 

[veronika_bebs]

The equation of a circle of radius r centered at the point (a,b) is given by (x-a)²+(y-b)²=r². Since you already are given the point (a,b), all you need to find is the radius of the circle. Can you use the information that a y-intercept is (0,1) to find the radius?

Thank you so much I didn't know it was that simple xD ok then can I ask something else:

A circle with a centre (5,4) intersects the x-axis 3 units from the origin. Find the possible equations of the circle.

Never mind i got it :D

 

[n!kofeyn]

Ok, cool!