Answer: Choice A) 3x3
The 3x3 refers to the number of rows and the number of columns in that order.
As another example, this matrix

is a 4x3 matrix because it has 4 rows and 3 columns.
I think it is the third one necause......
Answer:
About 5.73 cm
Step-by-step explanation:
C=2πr so
36=2πr (divide by 2)
18=πr (using 3.14 as π)
18=(3.14)r (divide by 3.14)
r=5.732484076 so
R≈5.73 cm