SOLUTION: prove that ( double angle formula) a) cos^2 2A = 4cos^4 A -4cos^2 A+1 can u plz me sloving this thx

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Question 1120331: prove that ( double angle formula)
a) cos^2 2A = 4cos^4 A -4cos^2 A+1
can u plz me sloving this
thx
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Factor the right side into (2 cos^2 A-1)^2
Take the square root
cos 2A=2 cos^2A-1