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AP EAMCET · Maths · Trigonometric Ratios & Identities

If \(\sin x+\sin y=\alpha, \cos x+\cos y=\beta\) then \(\operatorname{cosec}(x+y)=\)

  1. A \(\frac{\beta^2-\alpha^2}{\beta^2+\alpha^2}\)
  2. B \(\frac{2 \alpha \beta}{\beta^2-\alpha^2}\)
  3. C \(\frac{\alpha^2+\beta^2}{2 \alpha \beta}\)
  4. D \(\frac{2 \alpha \beta}{\beta^2+\alpha^2}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{\alpha^2+\beta^2}{2 \alpha \beta}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \text { Since } \sin x+\sin y=\alpha \\ & \Rightarrow 2 \sin \left(\frac{x+y}{2}\right) \cos \left(\frac{x-y}{2}\right)=\alpha \end{aligned}\) Since, \(\cos x+\cos y=\beta\)…