Let \(\frac{\pi }{2} [JEE Main 2026, 23 Jan (Shift 2)]

Let \(\frac{\pi }{2}<\theta <\pi\) and \(\text{cot}\theta =−\frac{1}{2\sqrt{2}}\). Then the value of \(\text{sin}\left(\frac{15\theta }{2}\right)\left(\text{cos}8\theta +\text{sin}8\theta \right)\) \(+\text{cos}\left(\frac{15\theta }{2}\right)\left(\text{cos}8\theta −\text{sin}8\theta \right)\) is equal to

[JEE Main 2026, 23 Jan (Shift 2)]