Question

Alguém pode me responder, por favor? com cálculo

Answer 1

Olá!
 
    Sejam x e y tais ângulos. De acordo com o enunciado, temos:


$\left\{\begin{array}{lcr}x + y & = & 78\\ x & = & \frac{3}{5}(90-y)\end{array}\right.\Leftrightarrow \left\{\begin{array}{lcr} x+y&=&78\\ 5x+3y&=&270\end{array}\right.\sim\\ \\ \\ \sim \left\{\begin{array}{lcr}x+y&=&78\\ -2y&=&-120 \end{array}\right.\Rightarrow \left\{\begin{array}{lcr}x+y&=&78\\ y&=&60\end{array}\right.\Rightarrow\\ \\ \\ \Rightarrow \left\{\begin{array}{lcr}x+60&=&78\\ y&=&60\end{array}\right. \Rightarrow\left\{\begin{array}{lcr}x&=&18\\ y&=&60\end{array}\right. .$


Portanto, resposta (D).



Bons estudos!