Question

Calculati sinx daca tgx/2=1/2

Answer 1

   
[tex]\displaystyle\\ \sin x= \frac{2\text{tg} \dfrac{x}{2} }{1+\text{tg}^2 \dfrac{x}{2}}= \frac{2\cdot\dfrac{1}{2} }{1+ \left(\dfrac{1}{2}\right)^{\b2}}= \frac{1 }{1+ \dfrac{1}{4}}=\frac{~~1~~}{\dfrac{5}{4}}=\boxed{\bf\dfrac{4}{5}}[/tex]