Question

Calcule a expressão X= SEN 90 SEN 270 +SEN90 COS180 \\\\\\\\\\\\\\ SEN90+ COS2 180

Answer 1

$\boxed{\begin{array}{l}\sf x=sen(90^\circ) \cdot sen(270^\circ)+sen(90^\circ)\cdot cos(180^\circ)\\\sf=1\cdot(-1)+1\cdot(-1)=-1-1=-2\\\sf sen(90^\circ) +cos(2\cdot180^\circ)=1+1=2\end{array}}$