lf the function f(x)=⎧⎪ ⎪ ⎪ ⎪ ⎪ ⎪⎨⎪ ⎪ ⎪ ⎪ ⎪ ⎪⎩1−cos4xx2ifx<0aifx=0√x√16+√x−4ifx>0is continuous at x=0 then a=