f(x)=(1-x)/(1+x)  হলে,  f(costheta)=? 

Explanation:

Another Explanation (5): দেওয়া আছে, \( f(x) = \frac{1-x}{1+x} \) তাহলে, \( f(\cos\theta) = \frac{1-\cos\theta}{1+\cos\theta} \) 🧐 আমরা জানি, \( 1 - \cos\theta = 2\sin^2(\frac{\theta}{2}) \) এবং \( 1 + \cos\theta = 2\cos^2(\frac{\theta}{2}) \) 😎 সুতরাং, \( f(\cos\theta) = \frac{2\sin^2(\frac{\theta}{2})}{2\cos^2(\frac{\theta}{2})} \) \( = \frac{\sin^2(\frac{\theta}{2})}{\cos^2(\frac{\theta}{2})} \) \( = \tan^2(\frac{\theta}{2}) \) 🎉 অতএব, \( f(\cos\theta) = \tan^2(\frac{\theta}{2}) \) 🙌