Question #ae98e

1 Answer
Oct 14, 2017

LHS=sin^4t + cos^4t

= (cos^2t +sin^2t) ^2-2sin^2tcos^2t

=1^2-1/2(2sintcost)^2

=1-1/2(sin2t)^2

=1-1/2sin^2 2t

=1-1/4*2sin^2 2t

=1-1/4(1-cos4t)

=1-1/4+1/4cos4t

= 3/4 + 1/4 cos4t=RHS