Question

Two circles with equal radii are intersecting at the points $(0,1)$ and $(0,-1)$. The tangent at the point $(0,1)$ to one of the circle. Then the distance between the centres of these circles is:

• A. $1$
• B. $\sqrt{2}$
• C. $2\sqrt{2}$
• D. $2$

Answer 1

The correct option is D $2$

In $\Delta APO$
${\left(\frac{\sqrt{2}r}{2}\right)}^2+1^2+r^2$
$⟹r=\sqrt{2}$
So distance between the centres $=\sqrt{2}r=2$.