Question

Sen⁴ x + cos⁴ x = 1-2 sen² x . cos² x

Tema: Identidades Trigonométricas

Answer 1

Hola!

${ \sin }^{4} (x) + \: { \cos}^{4} (x) = 1 - 2 { \sin }^{2} (x).{ \cos }^{2} (x) \\ { \sin }^{4} (x) + 2 { \sin }^{2} (x).{ \cos }^{2} (x) + \: { \cos}^{4} (x) = 1 \\ {({ \sin }^{2} (x) + { \cos }^{2}(x) )}^{2} = 1 \\{ \sin }^{2} (x) + { \cos }^{2}(x) = \sqrt{1} \\ { \sin }^{2} (x) + { \cos }^{2}(x) = 1$