- Atan30°
- Bcot40°
- Ctan40°
- Dtan80°
Step-by-Step Solution
Sum to product: sin70° + sin10° = 2·sin40°·cos30° and cos70° + cos10° = 2·cos40°·cos30°. The common factor 2cos30° cancels, leaving sin40°/cos40° = tan40° ≈ 0.839. Check: 1.1133/1.3268 = 0.839.
Answer: C) tan40°