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4 votes
1+ cos2x =
2/1+tan ²x

2 Answers

3 votes

sure but 1st show every1 wut u know

User Lfk
by
6.6k points
3 votes

Use the Pythagorean identity to rewrite the tangent:


\frac2{1+\tan^2x}=\frac2{\sec^2x}=2\cos^2x

Then use the double angle identity for cosine:


\cos^2x=\frac{1+\cos(2x)}2


\implies2\cos^2x=1+\cos(2x)

and the identity is proved.

User Ccampanale
by
6.7k points