9.55 degrees.
step-by-step explanation:
the given angle is
1 cycle is equal to 2π radians. so 4π will be equal to two cycles.
5.166667π-4π = 1.166667π
hence, this angle goes a little more than negative x axis.
1.166667π-π= 0.166667π
hence, the reference angle is 0.166667π radians.
1 radian = 57.2958 degrees
now, in degrees, this should be equals to 9.55 degrees.