[Toán 10] Bài tập lượng giác CM

I

i_am_challenger

[TEX]A=sin^2x.tan^2x+4sin^2x-tan^2x+3cos^2x[/TEX]

[tex]= tan^2x.(sin^2x - 1) + 3.(sin^2x + cos^2x) + sin^2x[/tex]

[tex]= - tan^2xcos^2x + 3 + tan^2x.cos^2x = 3[/tex]
 
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