Properties Of Triangles
In a triangle ABC, the cosine rule for side a is
Select the correct option:
Solution
a² = b² + c² - 2bc cos A
- The Law of Cosines: A generalization of the Pythagorean Theorem for any triangle.
- Formula: a2=b2+c2−2bccosA.
- Special Case: If ∠A=90∘, cos90∘=0, reducing it to a2=b2+c2.
- Alternative Form: cosA=2bcb2+c2−a2.
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About This Question
- Subject
- mathematics
- Chapter
- trigonometry
- Topic
- properties of triangles
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
a² = b² + c² - 2bc cos A
- The Law of Cosines: A generalization of the Pythagorean Theorem for any triangle.
- Formula: a2=b2+c2−2bccosA.
- Special Case: If ∠A=90∘, cos90∘=0, reducing it to a2=b2+c2.
- Alternative Form: cosA=2bcb2+c2−a2.
This easy difficulty mathematics question is from the chapter trigonometry, covering the topic of properties of triangles. It appeared in the 2025 exam.
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