7-11 Find the Fourier series of the function. 7. f(x) √1 if |x|<1 = f(x + 4) = f(x) 0 if 1|x|<2 0 if 2 x < 0 8. f(x)=1 1 if 0 < x < 1 f(x + 4) = f(x) 0 if 1 x < 2 X if -4x < 0 9. f(x) = f(x + 8) = f(x) 0 if 0 < x < 4 10. f(x) = 1−x, −1 ≤ x ≤1 11. f(t)=sin(3πt), -1≤t≤1 f(x + 2) = f(x)