Question

Sabendo x que cossec x = √3, calcule o valor de cos2x

Answer 1

Resposta:

cos2x = 1/3

Explicação passo a passo:

$cossecx=\sqrt{3}\implies senx=\frac{1}{\sqrt{3} } \\\\cos2x=cos^2x-sen^2x=1-sen^2x-senx=1-2sen^2x\\\\cos2x=1-2*(\frac{1}{\sqrt{3} })^2\\\\cos2x=1-\frac{2}{3}\\\\cos2x=\frac{1}{3}$