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Hi, I started doing this problem and I couldn't figure out the last two question where $cos(\frac{\theta}{2})= \frac{1-x^2}{1+x^2}$ and $sin(\frac{\theta}{2})= \frac{2x}{1+x^2}$ Could you explain to me where to start with these 2 questions. Thank you

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    $\begingroup$ Try drawing a triangle with opposite side equal to x and adjacent side 1 $\endgroup$ – Justin Stevenson Jan 24 at 19:56

These are trigonometric identities for half-angle formulas where in this case $x=\tan(\frac{\theta}{2})$



Do you know these identities?

And please take a look at this for better formatting enter link description here

  • $\begingroup$ this does not help at all. and thank you ill read it trough $\endgroup$ – Konstantin Uvarov Jan 24 at 20:00

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