Tích phân lượng giác?

C

catfass

$$cos^4 {x} =\frac{(1+cos2x)^2}{4}$$
$$sin^4 {x} =\frac{(1-cos2x)^2}{4}$$
[TEX]\Rightarrow cos^4 {x} +sin^4 {x} =\frac{1+ cos^2 {2x}}{2}[/TEX]
\Rightarrow [TEX]\int_{}^{}cos 2x(\frac{1}{2} +\frac{cos^2 {2x}}{2})[/TEX]
 
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