Fix an incorrect trigonometric answer

Press these keys

Walkthrough

1. 1
   Check angle mode

   Match DEGREE or RADIAN to the question.

2. 2
   Check inverse

   Use 2nd before SIN/COS/TAN only when finding an angle from a ratio.

3. 3
   Check all solutions

   A principal inverse result may have symmetric or periodic alternatives in the interval.

Worked example