Complementary Angles
ICSE · Class 9 · Mathematics
Flashcards for Complementary Angles — ICSE Class 9 Mathematics. Quick Q&A cards covering key concepts, definitions, and formulas.
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Get startedWhat are complementary angles? Give two examples.
Answer
Two acute angles are said to be complementary if their sum is 90°. Examples: 1. 30° and 60° are complementary (30° + 60° = 90°) 2. 45° and 45° are complementary (45° + 45° = 90°) 3. θ and (90° - θ) a…
If an angle measures 35°, what is its complement?
Answer
Complement of 35° = 90° - 35° = 55° General rule: For any angle θ, its complement = (90° - θ)…
State the relationship between sin θ and cos(90° - θ).
Answer
sin θ = cos(90° - θ) This means: The sine of an angle equals the cosine of its complement. Example: sin 30° = cos 60° = 1/2…
State the relationship between cos θ and sin(90° - θ).
Answer
cos θ = sin(90° - θ) This means: The cosine of an angle equals the sine of its complement. Example: cos 30° = sin 60° = √3/2…
What is the value of sin 40°/cos 50°?
Answer
sin 40°/cos 50° = sin 40°/cos(90° - 40°) = sin 40°/sin 40° = 1 Since cos 50° = cos(90° - 40°) = sin 40°…
State the relationship between tan θ and cot(90° - θ).
Answer
tan θ = cot(90° - θ) This means: The tangent of an angle equals the cotangent of its complement. Example: tan 45° = cot 45° = 1…
State the relationship between cot θ and tan(90° - θ).
Answer
cot θ = tan(90° - θ) This means: The cotangent of an angle equals the tangent of its complement. Example: cot 30° = tan 60° = √3…
Evaluate: tan 25°/cot 65°
Answer
tan 25°/cot 65° = tan 25°/cot(90° - 25°) = tan 25°/tan 25° = 1 Since cot 65° = cot(90° - 25°) = tan 25°…
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