Spectrum 2 years ago tan^2 x = 1-cos2x/ 1+ cos2x true or false?

1. zordoloom

That would be true. It' an identity.

2. checkoutmymath

It's not an identity. Does tan^2x = 1-(cos2x/1)? I'm certain it doesn't. It does, however, equal to (1-cos2x)/2. This is an example of a half-angle identity.

3. Spectrum

er....er

4. Jnlucero

$\frac{ 1-\cos 2x }{ 1+\cos 2x }=\frac{ 1-(1-2\sin^2x) }{ 1+(2\cos^2x-1) }=\frac{ 2\sin^2x }{2\cos^2x }=\tan^2x$

5. Jnlucero

so its true.

6. Spectrum

um 0.0 :/

7. Jnlucero

something wrong?

8. Spectrum

you guys are confusting me 0.o true or no?

9. Jnlucero

the first i did was to use the double angle formula for sine and cosine. then it was simplified, then since the ratio of sine and cosine is tangent, then the next step is obvious.