Question

sabendo que x e um ângulo do 3° quadrante , para quais valores reais de M temos cos(x) = 2* m/5​

Answer 1

LETRA B

Comentário :

$\displaystyle \sf cos(x)=\frac{2m}{5} \ \ ;\ \ x \in 3^{\circ} \ Quadrante \\\\\\ \underline{\text{O terceiro quadrante vai de } \pi \ a \ \frac{3\pi}{2}, \ ent{\~a}o : } \\\\\\ cos(\pi ) \leq cos(x) \leq cos\left(\frac{3\pi}{2}\right) \\\\\\ -1 \leq \frac{2m}{5}\leq 0 \\\\\\ \underline{lado \ esquerdo} : \\\\ \frac{2m}{5}\geq -1\to \boxed{\sf m\geq \frac{-5}{2}} \\\\\\ \underline{lado\ direito}: \\\\ \frac{2m}{5}\leq 0 \to \boxed{\sf m\leq 0} \\\\\\ \underline{Portanto}:$

$\huge\boxed{\displaystyle \sf m \in \left[\frac{-5}{2} \ , \ 0\ \right]}\checkmark$

LETRA B