Помогите, прошуу

1) tg20° + tg40°

2) tg п/3 - tg п/4

3) 1 + 2cos t

4) cos t + sin t

Решение

) tg20° + tg40° = sin (20 ° - 40°) / [cos20°sin40°] =

= - 2sin20° / [cos20° * 2sin20°cos20°] = - 1/cos²20°

2) tg п/3 - tg п/4 = 1 / √3 - 1 = (1-√3) / √3 = [ (1-√3) * √3] / 3

3) 1 + 2cos t = (1 + cost) + cost = 2cos ² (t/2) + 2cos² (t/2) - 1=

= 4cos² (t/2) - 1

4) cos t + sin t = √2 (cos45° - t)