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TS EAMCET · Maths · Trigonometric Ratios & Identities

If \(\cos \mathrm{A}+\cos \mathrm{B}+\cos \mathrm{C}=0=\sin \mathrm{A}+\sin \mathrm{B}+\sin \mathrm{C}\), then \(\cos (\mathrm{A}-\mathrm{B})+\cos (\mathrm{B}-\mathrm{C})+\cos (\mathrm{C}-\mathrm{A})=\)

  1. A 0
  2. B \(\frac{1}{2}\)
  3. C \(\frac{3}{2}\)
  4. D \(\frac{-3}{2}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\frac{-3}{2}\)

Step-by-step Solution

Detailed explanation

\(\cos \mathrm{A}+\cos \mathrm{B}+\cos \mathrm{C}=0\) ...(i) \(\sin A+\sin B+\sin C=0\) ...(ii) Squaring (i) and (ii) and add,…