Question #77e3a

1 Answer
Dec 21, 2016

LHS=2sin^6x+2cos^6x+1LHS=2sin6x+2cos6x+1

=2((sin^2x)^3+(cos^2x)^3+1=2((sin2x)3+(cos2x)3+1

=2((sin^2+cos^2x)^3-3sin^2xcos^2x(sin^2x+cos^2x)+1=2((sin2+cos2x)33sin2xcos2x(sin2x+cos2x)+1

=2*(1)^3-3*2*sin^2xcos^2x*(1)+1=2(1)332sin2xcos2x(1)+1

=3-3*2*sin^2xcos^2x=332sin2xcos2x

=3(1^2-2*sin^2xcos^2x)=3(122sin2xcos2x)

=3((sin^2x+cos^2x)^2-2*sin^2xcos^2x)=3((sin2x+cos2x)22sin2xcos2x)

=3((sin^2x)^2+(cos^2x))^2=3((sin2x)2+(cos2x))2

=3(sin^4x+cos^4x)=3(sin4x+cos4x)

=3sin^4x+3cos^4x=RHS=3sin4x+3cos4x=RHS

Proved