SOLUTION: this is my problem that i cannot solve.. sin^4 - cos^4 = 2sin^2 - 1 we can only work on one side of the problem. this is what i have got so far (sin^2 + cos^2) (sin^2 - cos^2

Algebra ->  Trigonometry-basics -> SOLUTION: this is my problem that i cannot solve.. sin^4 - cos^4 = 2sin^2 - 1 we can only work on one side of the problem. this is what i have got so far (sin^2 + cos^2) (sin^2 - cos^2      Log On


   



Question 282252: this is my problem that i cannot solve.. sin^4 - cos^4 = 2sin^2 - 1
we can only work on one side of the problem.
this is what i have got so far
(sin^2 + cos^2) (sin^2 - cos^2)=
1(sin^2 - cos^2)=
sin^2 - cos^2
I'm not sure what to do from there to make it equal 2sin^2 - 1

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
sin^4 - cos^4 = 2sin^2 - 1
(Sin^2+cos^2)(sin^2-Cos^2)
1*(Sin^2-Cos^2)
(1-cos^2)+sin^2 -1
Sin^2+sin^2-1
2Sin^2-1