AP EAMCET201823 Apr 2018Evening ShiftMathematicsCircleActual
If a circle touches the lines 3 x-4 y-10=0 and 3 x-4 y+30=0 and its centre lies on the line x+2 y=0 , then the equation of the circle is
Options
- Ax^2+y^2+4 x-2 y-11=0
- Bx^2+y^2+2 x-4 y-11=0
- Cx^2+y^2-4 x+2 y-11=0
- Dx^2+y^2+2 x-y-11=0
Correct answer
A. x^2+y^2+4 x-2 y-11=0
Step-by-step solution
Distance between parallel lines 3 x-4 y-10=0 and 3 x-4 y+30=0 is the length of diametre of required circle, so radius = 1 2 40 9+16 =4 and mid-point of intersection of lines 3 x-4 y-10=0, x+2 y=0 and 3 x-4 y+30=0 , x+2 y=0 , is the centre of required circle, so centre is ( 2-6 2 , -1+3 2 )=(-2,1) , then equation of required circle is, x^2+y^2+4 x-2 y-11=0 .