grei
Posts:
132
Registered:
11/27/12


Re: need help for the circle _
Posted:
Jul 9, 2013 9:27 AM


The fact that the circle is TANGENT to the y axis means that the radius from the center of the circle, (5, 2), to that point is perpendicular to the yaxis. And since the yaxis is vertical, that radius is horizontal. That means the circle is tangent to the yaxis at (0, 2). And that, in turn, means that the radius of the circle is 5.
The point (4, 3) will lie on that circle if and only if the distance from (5, 2) to (4, 3) is 5.

