3.Trigonometrical Ratios, Functions and Identities
medium

यदि $\alpha + \beta + \gamma = 2\pi ,$ तो

A

$\tan \frac{\alpha }{2} + \tan \frac{\beta }{2} + \tan \frac{\gamma }{2} = \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2}$

B

$\tan \frac{\alpha }{2}\tan \frac{\beta }{2} + \tan \frac{\beta }{2}\tan \frac{\gamma }{2} + \tan \frac{\gamma }{2}\tan \frac{\alpha }{2} = 1$

C

$\tan \frac{\alpha }{2} + \tan \frac{\beta }{2} + \tan \frac{\gamma }{2} = - \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2}$

D

इनमें से कोई नहीं

(IIT-1979)

Solution

(a) यहाँ $\alpha  + \beta  + \gamma  = 2\pi  $

$\Rightarrow \frac{\alpha }{2} + \frac{\beta }{2} + \frac{\gamma }{2} = \pi $

$ \Rightarrow \tan \left( {\frac{\alpha }{2} + \frac{\beta }{2} + \frac{\gamma }{2}} \right) = \tan \pi  = 0$

$ \Rightarrow \tan \frac{\alpha }{2} + \tan \frac{\beta }{2} + \tan \frac{\gamma }{2} – \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2} = 0$

$ \Rightarrow \tan \frac{\alpha }{2} + \tan \frac{\beta }{2} + \tan \frac{\gamma }{2} $

$= \tan \frac{\alpha }{2}\tan \frac{\beta }{2}\tan \frac{\gamma }{2}$.

.

Standard 11
Mathematics

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