Answer: C
Explanation:
The arc length, s, equals the radius, r, times the central angle, θ, given in radians. (In shorthand, s=r⋅θ.) If r=5 cm and θ=6 radians, the arc length is 5 cm⋅6=30 cm. If r=7 cm and θ=5 radians, the arc length is 7 cm⋅5=35 cm. If r=9 cm and θ=4 radians, the arc length is 9 cm⋅4=36 cm. An angle of 180∘ is π radians, or about 3.14. If r=10 cm, the arc length is 10 cm⋅3.14=31.4 cm. Of these choices, the longest arc is 36 cm.