Вычислите 1-√3ctg40+1/cos20

Question

Вычислите 1-√3ctg40+1/cos20

Answer 1

1 -√3*ctq40°+1/cos20° =1 -√3scos40°/sin40° +1/cos20° =
((sin40°-√3cos40°) +2sin20°)/sin40°=(2sin(40° - 60°)+2sin20° )/sin40°=
(2sin(-20°) +2sin20°)/sin40° = (-2sin20° +2sin20°)/sin40° =0/sin40° =0.