Mixing radian and degree angle units makes this a bit more challenging.
Try this:
yfcn = @(a) sin(a) .* ((120*pi/180 < a) & (150*pi/180 > a));
x = 0:0.1:pi;
figure
plot(x, yfcn(x))
grid
Note that in your original code, ‘theta’ and ‘x’ are vastly different sizes, so the plot would never work regardless. Beyond that, to compare vector elements, use single logical operators, not double logical operators.
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