Question 765165
{{{(cos(x))^4 + (sin(x ))^2= (cos(x))^2 + (sin(x))^4}}}
Rewrite identity {{{(cos(x))^4 - (sin(x ))^4= (cos(x))^2 - (sin(x))^2}}}
{{{((cos(x))^2)^2 - ((sin(x ))^2)^2= (cos(x))^2 - (sin(x))^2}}}
use {{{a^2-b^2=(a-b)(a+b)}}} and {{{(cos(x))^2 +(sin(x))^2=1}}}
{{{((cos(x))^2- (sin(x ))^2)((cos(x))^2 + (sin(x))^2)= (cos(x))^2 - (sin(x))^2}}}
{{{((cos(x))^2- (sin(x ))^2)*1= (cos(x))^2 - (sin(x))^2}}}
{{{(cos(x))^2- (sin(x ))^2= (cos(x))^2 - (sin(x))^2}}} correct identity