AP EAMCET202420 May 2024Morning ShiftMathematicsParabolaActual
A common tangent to the circle x^2+y^2=9 and parabola y^2=8 x is
Options
- A3 x- 3 y+2=0
- Bx- 3 y+6=0
- C2 x- 3 y+3=0
- Dx-3 y+6=0
Correct answer
B. x- 3 y+6=0
Step-by-step solution
Let y=m x+c be the equation of common tangent to parabola y^2=8 x and x^2+y^2=9 Condition for y=m x+c to be the tangent of y^2=4 a x is c= a m So, c= 2 m ....(i) The line y=m x+c is tangent to circle x^2+y^2=9 c m^2+1 =3 2 m^2+1 =3 m 4 m^2+1 =9 m^2 9 m^4+9 m^2-4=0 m^2= 1 3 , -4 3 m= 1 3 , -1 3 c=2 3 ,-2 3 y= 1 3 x+2 3 x- 3 y+6=0