Question

Se cere unghiul alfa. Va rog, dau coroana la primul răspuns corect!!​

Answer 1

 

$\displaystyle\bf\\\text{Avem de rezolvat ecuatia:}\\\\\sin^2\alpha-3\sin\alpha=0\\\\\text{Facem substitutia: }~~~\boxed{x=\sin\alpha}\\\\\text{Ecuatia devine: }\\\\x^2-3x=0\\\\x(x-3)=0\\\\x=0\implies x_1=0\\x-3=0\implies x_2=3\\\\\text{Ne intoarcem la substitutie.}\\x_1=0\implies\sin\alpha=0\implies\boxed{\bf\alpha=0+k\pi,~k\in N}\\\\x_2=3\implies\sin\alpha=3~~~\text{FALS deoarece}~~-1\leq sin\leq 1$