Can somone answer these? free brainliest

Two

The short answer is that it multiplies by 3.
Argument
First take an example. Use the one you were given
The small circle
The small circle starts out with a diameter of 5. So find the circumference.
d = 2r
r = d/2
r = 5/2 = 2.5

Circumference = 2 pi r
Circumference = 2 * 3.14 * 2.5
Circumference = 15.7

 The large circle
The large circle has a diameter 3 times as big. 
D = 15
r = d/2
r = 15/2
r = 7.5

Circumference = 2 pi r
Circumference = 2 * 3.14 * 7.5
Circumference = 47.1 

What are the ratios of these two numbers?
ration = 37.1 / 15.7 = 3
B <<<<< Answer  

Three
Short C
Comment
Think of the conversion as pi radians = 180 degrees just as you would say 3.78 L = 1 US gallon. The definition you have been offered will get you into trouble if you don't read it properly.

Solution
Change the 3/2 * pi radians into 1.5*pi radians
pi radians / 180 = 1.5 pi radians / x where x is the angle in degrees. Divide both sides by pi.

1 / 180 = 1.5 / x Cross multiply
1*x = 180 * 1.5
x = 270

C <<<< answer.