\(tan\left(x\right)=\dfrac{4}{3}=\dfrac{sin\left(x\right)}{cos\left(x\right)}\\\Rightarrow sin\left(x\right)=\dfrac{4}{3}cos\left(x\right)\\ \Rightarrow sin^2\left(x\right)=\dfrac{16}{9}cos^2\left(x\right)\)
mà \(sin^2\left(x\right)+cos^2\left(x\right)=1\)
\(\Rightarrow\dfrac{25}{9}cos^2\left(x\right)=1\\ \Rightarrow cos^2\left(x\right)=\dfrac{9}{25}\Rightarrow cos\left(x\right)=\dfrac{3}{4}\)
tik mik nha
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