The correct option is D b is an irrational number
f(x)=sin−1(x2−2x+2)
Domain of inverse sin function is [−1,1]
x2−2x+2=(x−1)2+1≥1
Clearly, the function f(x) is defined only when x=1
Substitute x=1 in the above expression, we get
f(1)=sin−1(1)=π2
⇒a=1, b=π2