0
$\begingroup$

Difference in values of radius of a circle whose centre is at origin and which touches the circle $x^2+y^2 -6x -8y+21=0$ is... I am getting answer $1$ but correct answer is $4$..

$\endgroup$
1
$\begingroup$

The tangent circle $(x-3)^2+(y-4)^2=2^2$ has radius 2, and it is at distance 5 from the origin. A circle centered on the origin will be tangent to it with radius 5-2=3 and with radius 5+2=7 through the line $y=\frac 43 x$. Hence the difference between the two possible tangent circles is 7-3=4.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.