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AP EAMCET · Maths · Properties of Triangles

In \(\triangle \mathrm{ABC}\), if \(a: b: c=4: 5: 6\), then \(\cos \mathrm{A}: \cos \mathrm{B}: \cos \mathrm{C}=\)

  1. A \(12: 9: 2\)
  2. B \(6: 5: 4\)
  3. C \(7: 8: 9\)
  4. D \(14: 11: 6\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(12: 9: 2\)

Step-by-step Solution

Detailed explanation

\(\cos \mathrm{A} = \frac{b^2 + c^2 - a^2}{2bc} = \frac{5^2 + 6^2 - 4^2}{2 \cdot 5 \cdot 6} = \frac{25+36-16}{60} = \frac{45}{60} = \frac{3}{4}\)…