25) (sin(π/2) - cos π + tg(π/4)) / (2sin(π/6) - sin(3π/2)); 26) sin 270° + ctg 750°

Решение:

1. \( \frac{\sin(\frac{\pi}{2}) - \cos(\pi) + \operatorname{tg}(\frac{\pi}{4})}{2\sin(\frac{\pi}{6}) - \sin(\frac{3\pi}{2})} = \frac{1 - (-1) + 1}{2 \cdot \frac{1}{2} - (-1)} = \frac{1+1+1}{1+1} = \frac{3}{2} \)
2. \( \sin(270^{\circ}) + \operatorname{ctg}(750^{\circ}) = -1 + \operatorname{ctg}(750^{\circ} - 2 \cdot 360^{\circ}) = -1 + \operatorname{ctg}(30^{\circ}) = -1 + \sqrt{3} \)

Ответ: 25) 3/2; 26) -1 + √3.