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MHT CET · Maths · Trigonometric Ratios & Identities

\(\frac{\sin A+\sin 7 A+\sin 13 A}{\cos A+\cos 7 A+\cos 13 A}=\)

  1. A \(\cot 7 A\)
  2. B \(\tan 6 A\)
  3. C \(\tan 7 A\)
  4. D \(\cot 6 A\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\tan 7 A\)

Step-by-step Solution

Detailed explanation

\(\frac{\sin A+\sin 7 A+\sin 13 A}{\cos A+\cos 7 A+\cos 13 A} =\frac{(\sin A+\sin 13 A)+\sin 7 A}{(\cos A+\cos 13 A)+\cos 7 A} \)
\( =\frac{2 \sin 7 A \cos 6 A+\sin 7 A}{2 \cos 7 A \cos 6 A+\cos 7 A} \)
\( =\frac{\sin 7 A(2 \cos 6 A+1)}{\cos 7 A(2 \cos 6 A+1)} \)
\( =\tan 7 A\)