Question

(1- cos25°+ cos50° / sin50°- sin25° )-tg 65. помогите решить

Answer 1

$...= \frac{1-cos25^{0}+2cos^{2}25^{0}-1}{2sin25^{0}cos25^{0}-sin25^{0}} -tg65^{0}= \frac{cos25^{0}(2cos25^{0}-1)}{sin25^{0}(2cos25^{0}-1)} -tg65^{0}$$= \frac{cos25^{0}}{sin25^{0}} -tg65^{0}=ctg25^{0}-tg65^{0}=ctg(90^{0}-65^{0})-tg65^{0}$$=tg65^{0}-tg65^{0}=0$