9. It is a closed plane figure made up of points.
a. circle
b. polygon
C. polyhedron
10. It is a line segment from the center to any point on the circle.
a. chord
b. diameter
c. radius
11. A diameter of a circle is 4 cm long. How long is a radius of that circle?
a. 2 cm
b. 3 cm
c. 5 cm
12. A radius of a circle is 9 cm long. How long is a diameter of that circle?
a. 10 cm
b. 15 cm
c. 18 cm​