cos 75^o এর মান কত?

Explanation:

Another Explanation (5): ```html cos 75<sup>o</sup> এর মান নির্ণয়: আমরা জানি, cos (A + B) = cos A cos B - sin A sin B সুতরাং, cos 75<sup>o</sup> = cos (45<sup>o</sup> + 30<sup>o</sup>) = cos 45<sup>o</sup> cos 30<sup>o</sup> - sin 45<sup>o</sup> sin 30<sup>o</sup> আমরা জানি, cos 45<sup>o</sup> = \(\frac{1}{\sqrt{2}}\) 🤓 cos 30<sup>o</sup> = \(\frac{\sqrt{3}}{2}\) 🤩 sin 45<sup>o</sup> = \(\frac{1}{\sqrt{2}}\) 🥳 sin 30<sup>o</sup> = \(\frac{1}{2}\) 😎 অতএব, cos 75<sup>o</sup> = \(\frac{1}{\sqrt{2}}\) * \(\frac{\sqrt{3}}{2}\) - \(\frac{1}{\sqrt{2}}\) * \(\frac{1}{2}\) = \(\frac{\sqrt{3}}{2\sqrt{2}}\) - \(\frac{1}{2\sqrt{2}}\) = \(\frac{\sqrt{3} - 1}{2\sqrt{2}}\) 🥰 সুতরাং, cos 75<sup>o</sup> = \(\frac{\sqrt{3} - 1}{2\sqrt{2}}\) 🎉 ```