How to verify identities in trigonometry

Check $1 - cos (2θ) - tan (θ) sin (2θ)$ Start on the left side, as it has more going on. Using basic trigger identities, we know that tanning (θ) can be converted into sin (θ)/cos (θ) that makes all the blue and cosines. $1 - cos (2θ) - (Sin (θ) / Kos (θ)) Sin (2θ)$$ Distribution of the right side of the equation: $$1 - cos (2θ) - ... ................
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