Question

A circle with centre $(a,b)$ passes through the origin. The equation of the tangent to the circle at the origin is

• A. $ax-by=0$
• B. $ax+by=0$
• C. $bx-ay=0$
• D. $bx+ay=0$

Answer 1

The correct option is B $ax+by=0$


Equation of circle passing through origin with centre $(a,b)$ is
$S:x^2+y^2-2ax-2by=0$

Tangent at $(0,0)$ to $S$ is,
$-ax-by=0\Rightarrow ax+by=0$