MHT CET · Maths · Trigonometric Ratios & Identities
In a triangle \(A B C\) with usual notations, If \(a: b: c=7: 8: 9\) : then \(\cos A: \cos B: \cos C=\)
- A 14:11:6
- B 7:8:9
- C 3:4:5
- D 5:6:7
Answer & Solution
Correct Answer
(A) 14:11:6
Step-by-step Solution
Detailed explanation
Let \(a=7 k, b=8 k, c=9 k\)
Using cosine rule \(\cos A=\frac{2}{3}, \cos B=\frac{11}{21}, \cos C=\frac{2}{7}\)
\(\Rightarrow \cos A: \cos B: \cos C=14: 11: 6\)
Using cosine rule \(\cos A=\frac{2}{3}, \cos B=\frac{11}{21}, \cos C=\frac{2}{7}\)
\(\Rightarrow \cos A: \cos B: \cos C=14: 11: 6\)
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