Question

Find the radius of the circle whose centre is $(3,2)$ and passes through $(-5,6)$.

• A. $4\sqrt{5}$
• B. $2\sqrt{5}$
• C. $4\sqrt{2}$
• D. None of these

Answer 1

The correct option is A $4\sqrt{5}$

Radius of the circle whose centre is $(3,2)$ and passes through $(-5,6)$ is the distance between $(3,2)$ and $(-5,6)$

$=\sqrt{(x_2-x_1{)}^2+(y_2-y_1{)}^2}$

$=\sqrt{(-5-3{)}^2+(6-2{)}^2}$

$=\sqrt{(-8{)}^2+(4{)}^2}$

$=\sqrt{64+16}$

$=\sqrt{80}$

$=4\sqrt{5}$ Units.