Two circles in the first quadrant of radii r 1 and r 2 touch the coordinate axes. Each of them cuts off an…

Two circles in the first quadrant of radii r1 and r2 touch the coordinate axes. Each of them cuts off an intercept of 2 units with the line x+y=2. Then r12+r22-r1r2 is equal to ____.

Solution

Assuming a circle of radius r which touches both the axis is given by, x-r2+y-r2=r2

Now given line x+y=2 makes the intercept 2 the circle, so plotting the diagram we get,

Now from diagram,

AC=BC=1, OC=r2-1

Now using the formula of perpendicular distance of point from the line we get,

OC=2r-22=r2-1

2r-12=r2-1

r2-4r+3=0

r1=1, r2=3

Hence,  r12+r22-r1r2=1+9-3=7 

Asked in: JEE Main 2023 (12 Apr Shift 1)

Practice more Circle questions on Aicharya