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How do you express functions in terms of the same function which has a positive acute angle.
You need a reference angle,
and you need the sign of
the original function.
The sign is negative because sin is negative in the 3rd Quadrant.
The reference angle is the acute angle between the terminal side
of 220 degrees and the closest segment of the x-axis.
That angle is 220-180 = 40 degrees.
So sin(220) = -sin(40)