Question

C(r) is a circumference function. find C(5) when C(r)=6.28r

Answer 1

In this case, they tell you that C(5) is a function of C(r). Notice the difference in these two; they say that C(5) is actually equal to C(r) meaning that r = 5! This way, plug 5 into the C(r) function to get 6.28 times 5, which gives you 31.4. 

I hope this helped! If it did please rate, thank, and give brainliest answer! 

Answer 2

C(r)

so for C(5)  r=5

6.28 x 5 = 31.4 is the answer