Nếu cot 1,25. tan (4 pi+1,25)-sin(x+ pi/2).cos(6 pi-x)=0 thì tan x bằng?
Giải thích
\(\cot 1,25.\tan \left( {4\pi + 1,25} \right) - \sin \left( {x + \frac{\pi }{2}} \right).\cos \left( {6\pi - x} \right) = 0\)
⇔ 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.