nếu cot 1 25

Lời giải:

\(\cot 1,25.\tan \left( {4\pi + 1,25} \right) - \sin \left( {x + \frac{\pi }{2}} \right).\cos \left( {6\pi - x} \right) = 0\)

⇔ cot1,25 . tan1,25 – cosx.cos(-x) = 0

⇔ 1 – cos²x = 0

⇔ sin²x = 0

⇔ sinx = 0

Suy ra: \(\tan x = \frac{{\sin x}}{{\cos x}} = 0\)

Vậy tan x = 0.