The tangent line equation is tangent to a circle at
.
The tangent line equation is tangent to a circle at
.
If a line is tangent to a circle, then the line perpendicular to the tangent line passing through the point of tangency also passes through the center of the circle.
\Find the perpendicular lines of tangent lines.
\These lines passes through the center of the circle.
\ \Consider the equation .
Write the equation in slope-intercept form , where
is slope and
is
-intercept.
.
Slope of the line is .
Perpendicular line slope is .
Perpendicular line passes through .
Substitute and
in
.
.
Another tangent equation .
Compare with .
Slope of the line is .
Perpendicular line slope is .
Perpendicular line passes through .
Substitute and
in
.
.
Find the intersection points of and
.
Substitute in
.
The intersection point is .
Center of the circle is .
Center of the circle is .