[Toán 11] Đề kiểm tra chương 1- Lượng giác

C

cobe_xauxi_ngungoc

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N

nguyenbahiep1

câu 1

[laTEX]dk: sin x \not = 0 \\ \\ cosx \not = 1[/laTEX]

câu 2

[laTEX]y = cos^2 x -2cosx + 5 \\ \\ -1 \leq u = cosx \leq 1 \\ \\ y = u^2 -2u+5 \\ \\ Min y = f(1) = 4 \Rightarrow cosx = 1 \\ \\ Max y = f(- 1) = 8 \Rightarrow cosx = - 1[/laTEX]

câu 3

câu 3

a)

[laTEX] 2(1+cos2x) +2cos^22x-1 -5 = 0 \\ \\ 2cos^22x +2cos2x - 4 \\ \\ TH_1: cosx = 1 \\ \\ TH_2: cosx = - 2 (L)[/laTEX]
 
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