What is the standard form of the equation of a circle passing through Center at the point (-3, 1) and tangent to the y-axis?

1 Answer
Jan 7, 2016

Answer:

#(x+3)^2+(y-1)^2=9#

Explanation:

I assume you meant "with center at #(-3,1)#"

The general form for a circle with center #(a,b)# and radius #r# is
#color(white)("XXX")(x-a)^2+(y-b)^2=r^2#

If the circle has its center at #(-3,1)# and is tangent to the Y-axis then it has a radius of #r=3#.

Substituting #(-3)# for #a#, #1# for #b#, and #3# for #r# in the general form gives:
#color(white)("XXX")(x-(-3))^2+(y-1)=3^2#
which simplifies to the Answer above.

graph{(x+3)^2+(y-1)^2=9 [-8.77, 3.716, -2.08, 4.16]}