Question:

A circle \(S\) passing through origin cuts another circle \[ x^2+y^2-6x+8y+16=0 \] orthogonally and makes a chord of maximum length on line \[ x-y-2=0 \] then one diameter of circle \(S\) is

Show Hint

Maximum chord of a circle along a line occurs when that line passes through the center.
Updated On: Jun 15, 2026
  • \(x+y=2\)
  • \(2x+3y=4\)
  • \(4x-5y+10=0\)
  • \(5x+6y+12=0\)
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is A

Solution and Explanation

Concept: Two circles cutting orthogonally satisfy: \[ 2g_1g_2+2f_1f_2=c_1+c_2 \] Maximum chord occurs when line passes through center.

Step 1:
Equation of variable circle.
Passing through origin. \[ x^2+y^2+2gx+2fy=0 \]

Step 2:
Orthogonal condition.
Given second circle: \[ g=-3,\qquad f=4,\qquad c=16 \] Apply condition \[ 2(g)(-3)+2(f)(4)=16 \] \[ -6g+8f=16 \] \[ -3g+4f=8 \]

Step 3:
Maximum chord condition.
Chord maximum when line passes through center. Center of circle \[ (-g,-f) \] Must lie on \[ x-y-2=0 \] So \[ -g+f-2=0 \] \[ f-g=2 \] Solve equations. \[ g=-1,\qquad f=1 \] Diameter line through center and origin: \[ x+y=2 \] Thus \[ \boxed{x+y=2} \]
Was this answer helpful?
0
0