Compound Angles
Easymathematics
The formula for cos(A + B) is
Select the correct option:
Solution
Incorrect! Answer:
cos A cos B - sin A sin B
- Addition Theorem: The cosine of a sum follows a 'like-with-like' pattern but flips the sign.
- Result: cos(A+B)=cosAcosB−sinAsinB.
- Rule: Cosine keeps c⋅c and s⋅s together, but + in the argument results in − in the expansion.
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About This Question
- Subject
- mathematics
- Chapter
- trigonometry
- Topic
- compound angles
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
cos A cos B - sin A sin B
- Addition Theorem: The cosine of a sum follows a 'like-with-like' pattern but flips the sign.
- Result: cos(A+B)=cosAcosB−sinAsinB.
- Rule: Cosine keeps c⋅c and s⋅s together, but + in the argument results in − in the expansion.
This easy difficulty mathematics question is from the chapter trigonometry, covering the topic of compound angles. It appeared in the 2025 exam.
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