I keep getting “Principal value branch” questions wrong in Relations, Functions & Inverse Trigonometry. What's the trap?
giving all possible angles instead of the principal value.
The usual trap: giving all possible angles instead of the principal value. How to avoid it: report the one angle inside the principal range. Go back to the definition — inverse trig functions are made single-valued by restricting their range to a principal branch (e.g. sin⁻¹ to [−π/2, π/2]).
Key point
Principal value branch
Common mistake
giving all possible angles instead of the principal value.
Memory tip
report the one angle inside the principal range.
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