Find the equation of the circle which has its centre at the point (3, 4) and touches the straight line 5x+12y−1=0
The centre of the required circle in (3, 4) and the circle touches the line 5x + 12y = 1 so, radius = OA = Perpendicular distance of O to 5x + 12y =1
[∵ radius is perpendicular to the tangent]
⇒OA=5×3+12×4−1√5+122=6213
Thus the equation of circle will be,
(x−3)2+(y−4)2=(6213)2⇒169[x2+y2−6x−8y]+25×169=3844⇒169[x2+y2−6x−8y]+381=0