Toán Lớp 11: Câu 1: 3 4$sinx^{2}$ + 2sin2x + 2 $cosx^{2}$ =1
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Toán Lớp 11: Câu 1: 3 4$sinx^{2}$ + 2sin2x + 2 $cosx^{2}$ =1
Comments ( 1 )
cosx =0 (l)
<=> 4sin^2x/cos^2x + 4sin x/cosx + 2cos^2x/cos^2 = 1/cos^2 x
<=> 4tan^2x + 4tanx + 2 =tan^2 +1
<=> 3tan^2x + 4tanx + 1 =0
<=> (tan x+1)(3tanx + 1) =0
tãn x =-1 ; x =-pi/4 +kpi
tan x =-1/3 ; x =arctan(-1 /3) +kpi