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