Complementary angle of 60° is:

Question

Complementary angle of 60° is:

1. A. 120°
2. B. 30° (Correct answer)
3. C. 60°
4. D. None of the above

Correct Answer

Option B — 30°

Detailed Solution & Explanation

The correct answer is 30°.

Key Points

• Two angles are complementary when they add to 90°.
• The complement of 60° is therefore 90° − 60° = 30°.
• 120° would be the supplement (adding to 180°), which is the intended trap.

Additional Information

• Keep the pair straight: complementary → 90°, supplementary → 180°. A memory hook is that C comes before S, and 90 before 180.
• In a right-angled triangle the two non-right angles are always complementary.
• sin θ = cos (90° − θ), which is why sin 60° = cos 30° — the trigonometric expression of complementarity.