How do you write an equation for a circle given center (-8,-7) and tangent to the y-axis?

1 Answer
Oct 9, 2016



The standard form of the equation of a circle is.

where (a ,b) are the coordinates of the centre and r, the radius.

here centre = (-8 ,-7) #rArra=-8" and " b=-7#

Since the y-axis is a tangent then the radius will be the horizontal distance from (-8 ,-7) to the y-axis ( x = 0). That is radius = 8.

substitute values into the standard equation.


#rArr(x+8)^2+(y+7)^2=64" is the equation of the circle"#
graph{(x+8)^2+(y+7)^2=64 [-31.6, 31.6, -15.8, 15.8]}