Question 729302
tan^2 x + cos^2 x = 1
(sin^2x/cos^2x)+cos^2x=1
LCD:cos^2x
sin^2x+cos^4x=cos^2x
1-cos^2x+cos^4x=cos^2x
cos^4x-2cos^2x+1=0
(cos^2x-1)(cos^2x-1)=0
(cosx+1)(cosx-1)(cosx+1)(cosx-1)=0
..
cosx=-1
x=π(multiplicity 2)
..
cosx=1
x=0 (multiplicity 2)