When working with cartesian coordinates,
the sin() will give the distance to be added/subtracted to the Y coordinate. Since 239+ degrees is in the third quadrant, the sin value is negative.
the cos() will give the distance to be added/subtracted to the X coordinate.
You can look at the sin/cos definitions to clarify this.
X2 = (75 * cos(239.2550)) + 2279540.5757
Y2 = (75 * sin(239.2550)) + 841723.9968
Your calculator should provide the correct sign for the sin/cos values.
However in this case BOTH the sin/cos values will be negative.