match them!

1. diameter
2. radius
3. area
4. circumference
5. semi circle
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a. the distance around a circle
b. a line segment that measures from on edge of a circle to the other and passes through the center
c. a line segment measuring from the center of the circle to its outer edge
d. the number of a square units used to cover the surface of a figure
e. half of a circle that is divided by the diameter