Common Mistakes
Frequent Errors
1. Stopping after one inverse-trig answer (3.10.A.1). 2. Missing symmetric solutions on [0, 2 pi) (3.10.A.2). 3. Listing solutions outside the stated interval. 4. Ignoring contextual domain that limits answers (3.10.A.3). 5. Inequality solution written as single angles instead of intervals. 6. Using wrong period (pi vs 2 pi) when adding k terms. 7. No substitution check after solving. 8. Applying inverse trig without domain validity for sin/cos inputs.
Why These Happen
Periodicity and multiple representations make it easy to lose track of the full solution set or the context window.
How to Fix Them
- Draw one period and mark all intersection points.
- Write "principal + symmetry + k*period" workflow explicitly.
- Substitute each candidate solution.
- Re-read the context for allowed times/angles.
Avoidance Scripts
- "Interval first; count solutions on it."
- "Inverse gives a start, not always the finish."
- "Context may throw some math answers away."
Quick Self-Check
- Did I find all solutions on the interval?
- Did I express inequalities as intervals?
- Did context eliminate any candidates?