I need help with these two!! thanks!!!

Answer:
11: Diameter
13: 10 cm
Step-by-step explanation:
Diameter is a straight line across a circle.
It would be 10 because if you cut 20 in half, which is the whole distance of the line, you would get 10.
Answer:
11. B. Diameter
13. B. 10cm
Circumference of circle= π*Diameter
MP is the diameter and it measures 20cm. MT is the radius. the radius is half the diameter.
MT= 20cm/2= 10cm