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COMEDK · Maths · 8. Trigonometric Ratios & Identities

The value of \(\cos \left(35^{\circ}+A\right) \cos \left(35^{\circ}-B\right)\)
\(+\sin \left(35^{\circ}+A\right) \sin \left(35^{\circ}-B\right)\) is equal to

  1. A \(\sin (A+B) \quad\)
  2. B \(\sin (A-B)\)
  3. C \(\cos (A+B) \quad\)
  4. D \(\cos (A-B)\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\cos (A+B) \quad\)

Step-by-step Solution

Detailed explanation

\(\cos \left(35^{\circ}+A\right) \cos \left(35^{\circ}-B\right) +\sin \left(35^{\circ}+A\right) \sin \left(35^{\circ}-B\right)\) \(=\cos \left[\left(35^{\circ}+A\right)-\left(35^{\circ}-B\right)\right]\) \(=\cos (A+B)\)