What is the reference angle in radians for 876°

First we should find the terminal side of 876° by subtracting 360° (for a full rotation) as many times possible until we get some where between 0° and 360°. Doing this we get 156° (876-360-360)

Second, knowing the unit circle, this measure is closest of the reference angle of 150°, which in radians is 5pi/4

I am not exactly sure if that is what you were asking for ... I apologize if any of this is pooly explained