Interaction between Two Circles

IMPORTANT

Interaction between Two Circles: Overview

This topic covers concepts, such as, Interaction between Two Circles, Relative Positions of Two Circles, Radical Centre of Three Circles & Centre of Similitude of Circle etc.

Important Questions on Interaction between Two Circles

EASY
IMPORTANT

Two circles touch each other internally. The radii of these circles are 2 cm  and 3 cm respectively. Find the length of the largest chord of the outer circle which touches the internal circle at a point?

HARD
IMPORTANT

The centres of two circles C1 and C2 each of unit radius are at a distance of 6 units from each other. Let P be the midpoint of the line segment joining the centres of C1 and C2 and C be a circle touching circles C1 and C2 externally. If a common tangent to C1 and C passing through P is also a common tangent to C2 and C, then the radius (in units) of the circle C is 

HARD
IMPORTANT

The radius of the circle, having centre at (2, 1), whose one of the chord is a diameter of the circle x 2 + y 2 - 2 x - 6 y + 6 = 0

MEDIUM
IMPORTANT

If the circle  C1:x2+y2=16 intersects another circle C 2 of radius 5 in such a manner that the common chord is of maximum length and has a slope equal to   3 4 , then the coordinates of the centre of C 2 are

EASY
IMPORTANT

The image of the point 3,4 with respect to the radical axis of the circles x2+y2+8x+2y+10=0 and x2+y2+7x+3y+10=0 is

MEDIUM
IMPORTANT

The angle between circles x2+y2+2x+4y+1=0 and x2+y2-2x+6y-3=0 is:

EASY
IMPORTANT

If S=x2+y2+2x+17y+4=0, S'=x2+y2+7x+6y+11=0 and S=x2+y2+2x+17y+4=0, S'=x2+y2+7x+6y+11=0 y2-x+22y+3=0 are three circles, then the length of tangent from their radical center to S=0 units

EASY
IMPORTANT

The perpendicular distance from the point 1,2 to common chord of the circles 2 x+4 y-4=0 and x2+y2+4x-6y-3=0 is units.

MEDIUM
IMPORTANT

Find the equation of a circle which cuts the circle x2+y2-6x+4y-3=0 orthogonally, while passing through (3, 0) and touching the y-axis.

HARD
IMPORTANT

Choose the correct option regarding the following statements:
Statement- 1: The length of common chord of the circles x2+y2+ax+by+c=0 and
x2+y2+bx+ay+c=0 equals (a+b)2-8c2
Statement- 2 : If two circles intersect at two distinct points, then their radical axis is their common chord.

EASY
IMPORTANT

If the circles x2+y2-6x-8y-12=0 and x2+y2-4x+6y+k=0 are perpendicular to each other, then 'k'' equals

HARD
IMPORTANT

Which circle among the following bisects the circumference of the circle x2+y2-8x-6y+23=0 ?

HARD
IMPORTANT

If L1 represents the radical axis of circles x2+y2-4x-6y+5=0 and x2+y2-2x-4y-1=0  and L2 represents the radical axis of x2+y2+2x+2y-7=0 and x2+y2+x+y+9=0, then _______

MEDIUM
IMPORTANT

Equation of the straight line meeting the circle with centre at origin and radius equal to 5 in two points at equal distances of 3 units from the point A3, 4 is

 

HARD
IMPORTANT

If the circles x2+y2=9 and x2+y2+2αx+2y+1=0 touch each other internally, then α is equal to

HARD
IMPORTANT

The number of common tangents to the circles x2+y2+2x+8y-23=0 and x2+y2-4x-10y+9=0, are

HARD
IMPORTANT

If the radical centre of the following circles: x2+y2+4x-7=0, 2x2+2y2+3x+5y-9=0, x2+y2+y=0 is a,b then find the value of a+b.

MEDIUM
IMPORTANT

The equation of the common chord of the pair of circles: (x-a)2+(y-b)2=c2, and (x-b)2+(y-a)2=c2(ab) is

EASY
IMPORTANT

The equation of the radical axis of the circles: x2+y2+2x+4y+1=0 and x2+y2+4x+y=0 is

EASY
IMPORTANT

The equation of the radical axis of the circles: x2+y2-3x-4y+5=0, and 3x2+y2-7x+8y-11=0 is