The value of b for which the roots of the equation sinx=b are in A.P is

The value of x for sin x= b, lie in 1st and 2nd quadrant or 3rd and 4th quadrants if b≠0,b≠±1  so they can not  form A.P. Roots of sin x = b will form A.P. if b=0 or 1 or –1