The range of sin(x) is [-1,1]. No matter what the value of x,pi,pi/2,pi/4,pi/6,-pi/2,etc the value of sinx will always be between -1 and 1(both included)
To write it as a fraction first count the number of decimals and call it (which, in our case, has a value of 3). Multiply the number with to get . Then divide this number by to get from here you can either simplify (if the assignment says so, then the simplified fraction is ) or not.