2.31 Without actually computing them, but using appro- priate sketches, tell if the Fourier transforms of the signals given below are real, imaginary, or neither; even, odd, or neither. Give your reasoning in each case. (a) x₁ (1) II(+1/2)-II (-1/2) (b) x2 (1)=II (1/2) + II (1) (c) x3 (1) sin (2лt) II (1) (d) x (t)=sin(2x1 + x/4) II (1) (e) x (1)=cos (2) II (1) (f) x6 (1) = 1/ [1 +(1/5)4]