Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
AP EAMCET202316 May 2023Morning ShiftMathematicsCircleActual

If the circles x^2+y^2-2 x+4 y+c=0 and x^2+y^2+2 x-4 y+c=0 have four common tangents, then

Options

  1. Ac < 0
  2. B-2 < c < 2
  3. C0 < c < 5
  4. Dc >0

Correct answer

C. 0 < c < 5

Step-by-step solution

The given equation of circle is as follows :- x^2+y^2-2 x+4 y+c=0 ...(i) x^2+y^2+2 x-4 y+c=0 ...(ii) Radius and centre of circle (i) is r₁= (-1)^2+(2)^2-c = 5-c and c₁=(+1,-2) Radius and centre of circle (ii) is r₂= (1)^2+(-2)^2-c = 5-c and c₂=(-1,2) Circle (i) and (ii) have four common tangents. aligned & r₁+r₂ 0 ...(i) Radius of circles should be positive. aligned & r₁>0 & 5-c >0 5-c>0 aligned c < 5 ...(ii) From eqn. (i) and (ii) 0 < c < 5 Option (3) is correct.

Practice Circle on Quantrex Academy →

More from Circle

A circle touches both the coordinate axes and the straight line L 4 x +3 y -6=0 in the first quadrant. If this circle lies below the line L =0 , then the equation of that circle is 2025If the smallest circle through the points of intersection of x^2+y^2=a^2 and x +y =p, 0 < p < a is x^2+y^2-a^2+ (x +y -p)=0 then = 2025If the lines 3 x-4 y+4=0 and 6 x-8 y-7=0 are the tangents to the same circle, then the area of that circle (in sq.units) is 2025Circles are drawn through the point (2,0) to cut intercepts of length 5 units on the X -axis. If their centre lie in the first quadrant, then their equation is 2025The circles x^2+y^2-2 x-4 y-4=0 and x^2+y^2+2 x+4 y-11=0 2025If the line 4 x-3 y+7=0 touches the circle x^2+y^2-6 x+4 y-12=0 at ( , ) , then +2 = 2025The slope of the common tangent drawn to the circles x^2+y^2-4 x+12 y-216=0 and x^2+y^2+6 x-12 y+36=0 is 2025If r₁ and r₂ are radii of two circles touching all the four circles (x r)^2+(y r)^2=r^2 , then r₁+r₂ r = 2025 Full Circle list All AP EAMCET PYQs