Question

Find an equation of the circle with center at (-2,3) that is tangent to the y-axis in the form of (x-a)^2+(y-b)^2=c where a, b, c are constants.

Answer 1

hello :
the center is : (a,b) when : a = - 2 and b= 3
an equation y-axis is x= 0
the ridus is the distance betwen the center and y-axis :
r = |(1)(-2)+(0)(3)+0 |/√((1)²+(0)²) = 2/1 =2
so : c=4.....( c = r²)
an equation of the circle is : (x+2)²+(y-3)² = 4