Question

Sabendo que senx =3/5 determine o valor de cos(2x) *

7/25
-7/25
√7/25
√7/5
NDA

Answer 1

Resposta:

7/25

Explicação passo-a-passo:

$sen^2 x + cos^2 x = 1 \\\ (\frac{3}{5})^2 + cos^2 x = 1 \\\\ \frac{9}{25} + cos^2 x = 1 \\\\ cos^2 x = 1 - \frac{9}{25} \\\\ cos^2 x = \frac{16}{25} \\\\ cos (2x) = cos^2 x - sen^2 x \\\ cos (2x) = \frac{16}{25} - (\frac{3}{5})^2 \\\\ cos (2x) = \frac{16}{25} - \frac{9}{25} \\\\ cos (2x) = \frac{7}{25}$

Espero ter ajudado.