Solve sin²A+cos A=1 for 0°≤A≤90°.
- Angle 0° only
- No angle solutions
- Angle 90° only
- Angles 0° and 90°
Show answer and solution
Correct answer: D. Angles 0° and 90°
Substitution gives cos A(1 − cos A) = 0, allowing cosine zero or one at the two endpoints.