arc length along x-axis

Move the green point to form a central angle of 1 radian. Given that the radius = 4 ft, what is the length of segment p in feet?

Move the green point to form a central angle of 2 radians. What is the length of segment p?

Move the green point to form a central angle radians. What is the length of segment p?

Move the green point to form a central angle 5 radians. What is the length of segment p?