Question

Sabendo que sen x = 3/5, calcule o valor de cos 2x.

Answer 1

Resposta:

$\textsf{Leia abaixo}$

Explicação passo-a-passo:

$\mathsf{cos\:2x = 1 - 2\:sen^2\: x}$

$\mathsf{cos\:2x = 1 - 2\large(\dfrac{3}{5}\large)^2}$

$\mathsf{cos\:2x = 1 - 2\large(\dfrac{9}{25}\large)}$

$\mathsf{cos\:2x = 1 -\dfrac{18}{25}}$

$\mathsf{cos\:2x = \dfrac{25 - 18}{25}}$

$\boxed{\boxed{\mathsf{cos\:2x = \dfrac{7}{25}}}}$