Answer:
(x-2)*x
Step-by-step explanation:
its maximum common divisor is x
let Φ be the central angle of the arc
pi*2r = 20
r = 10/pi
arc length= 2pi*r*(Φ/360°)
4 = 2pi*r*(Φ/360°)
Φ=2/10 * 360° =72° degree