Question

The circle of radius $a$ and center at origin $(0,0)$ passes through $(\sqrt{3},1)$, find $a$.

• A. $2$
• B. $4$
• C. $3$
• D. $1$

Answer 1

The correct option is A $2$

The circle center at origin and radius $a$ is given as $x^2+y^2=a^2$

it passes through $(\sqrt{3},1)$

$(\sqrt{3}{)}^2+1^2=a^2{a}^2=1+3a^2=4a=\pm 2$