TS EAMCET · Maths · Trigonometric Ratios & Identities
If \(\cos (A-B)=3 / 5\) and \(\tan A \tan B=2\), then which one of the following is true?
- A \(\sin (A+B)=\frac{1}{5}\)
- B \(\sin (A+B)=-\frac{1}{5}\)
- C \(\cos (A-B)=\frac{1}{5}\)
- D \(\cos (A+B)=-\frac{1}{5}\)
Answer & Solution
Correct Answer
(D) \(\cos (A+B)=-\frac{1}{5}\)
Step-by-step Solution
Detailed explanation
Given, \(\cos (A-B)=\frac{3}{5}\) and \(\tan A \tan B=2\) \(\Rightarrow \quad \frac{\sin A \sin B}{\cos A \cos B}=2\) Using componendo and dividendo…
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