how do i find the radius? please help :(

Answer:
r = 40/π exact answer
r = 12.7 decimal approximation
Step-by-step explanation:
arc length formula
s = (∅/360) * 2πr
s = (∅/180) * πr
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Plug in the givens
10 = (45/180) * πr
10 = .25πr
Divide both sides by .25
40 = πr
divide both sides by π
40/π = r
r = 40/π exact answer
r = 40/3.14
r = 12.7 decimal approximation