Question

find the equation of circle which is concentric with x^2+y^2-6x+7=0and touches the line x+y+3=0​

Answer 1

• centre of the required circle will be the same as the centre of the given circle which is (3,0)

• the required circle touches the line x+y+3 =0 , so the distance from its centre (3,0)to the given line gives radius of the required circle . , d = ax+by+c / √ (a²+b²) =) r = 3+0+3 √1²+1²= 3√2 unit

so the equ of the circle is given by (x-3)²+ y²= (3√2)²