Вычислите: а) cos 60°+ 2 sin 30°+ tg² 60°- ctg 45°; б) 3 cos 180°+ 5 ctg 270° - 2 tg 0°- sin 60°.

А)cos 60° + 2sin 30° + 1/2tg²60° - ctg 45° = 1/2 + 2 * 1/2 + 1/(2*(√3)² - 1 = 1/2 + 1 + 1/6 - 1 = 1/2 + 1/6 = 2/3
б)3cos 180° + 5ctg 270° - 2tg 0 - sin 60° = 3 * (-1) + 5 * ctg(360° - 90°) - 2 * 0 - √3/2 = = 2 * ctg(-90°) - 0 - √3/2 = -2ctg 90° - √3/2 = -2 * 0 - √3/2 = -√3/2