What is the reference angle for the angle with measure −π/4
1) What is -pi/4 in degrees? What quadrant is it in?
2) The reference angle is the one from the poisitve, or negative x axix.
Willl you use the positve x axis OR the negative x axis for this quadrant?
3) What reference (acute) angle will give the same trig ratios?
Think about my questions, if you get stuck let me know where :)
Here are a couple of general videos that might help with this topic.