# Sample quiz on equation of a circle Main home here.

1. If the equation of a circle is given as $x^2+y^2=r^2$, the center of the circle is located at $\cdots$?
$(r,r)$
$(r,0)$
$(0,0)$
$(0,r)$
2. What is the radius of a circle whose equation is given by $x^2+y^2=9$?
$3$
$9$
$27$
$81$
3. What is the radius of a circle whose equation is given by $x^2+y^2=2$?
$\sqrt{2}$
$2$
$4$
$8$
4. Find the coordinates of the center of a circle whose equation is $x^2+(y-1)^2=10$
$(0,0)$
$(0,1)$
$(1,0)$
$(1,1)$
5. Find the coordinates of the center of a circle whose equation is $(x+1)^2+y^2=9$
$(-1,-1)$
$(-1,1)$
$(-1,0)$
$(1,0)$
6. A circle is centered at $(2,0)$ and passes through $(5,4)$. Find its equation.
$(x+2)^2+y^2=25$
$(x-2)^2+y^2=5$
$(x+2)^2+y^2=5$
$(x-2)^2+y^2=25$
7. A circle has center at $(1,-1)$ and its radius is $4$. What is its equation?
$(x+1)^2+(y+1)^2=16$
$(x-1)^2+(y+1)^2=16$
$(x-1)^2+(y+1)^2=4$
$(x-1)^2+(y-1)^2=16$
8. Which of the following points is not inside the circle $x^2+y^2=100$?
$(8,5)$
$(9,2)$
$(3,9)$
$(9,6)$
9. Which of the following points is on the circle $(x-1)^2+(y-2)^2=16$?
$(6,1)$
$(1,6)$
$(-1,6)$
$(-2,-3)$
10. Find the equation of a circle which passes through $(0,0),(6,0),(0,8)$.
$x^2+y^2=5$
$x^2+y^2=36$
$(x+3)^2+(y+4)^2=25$
$(x-3)^2+(y-4)^2=25$