In a circle, an arc length of 6.6 is intercepted by central angle of 2/3 radians. Determine the length of the radius.

9.9

Step-by-step explanation:

To solve this problem, we first need to know that the whole length of the circunference is related to a central angle of 2pi radians. Then, we can solve using a rule of three to find the radius:

arc of 6.6 -> central angle of 2/3

arc of 2*pi*r -> central angle of 2pi

2*pi*r * (2/3) = 6.6 * 2*pi

r * (2/3) = 6.6

r = 6.6 / (2/3) = 9.9

So the length of the radius is 9.9

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

6 equilateral triangles