Cos=ac/ab=√15/((√5)^2+(√15)^2)=√15/√20=√15/2√5=<span>√3/2</span>
<span>2Fe + 3Cl</span>₂ <span>= 2FeCl</span>₃<span>
2Na + Br</span>₂ <span>= 2NaBr
4P+ 5O</span>₂ <span>= 2P</span>₂<span>O</span>₅<span>
2KClO</span>₃ <span>= 2KCl+ 3O</span>₂<span>
2FeCl</span>₂ <span>+ Cl</span>₂<span>= 2FeCl</span>₃<span>
2FeBr</span>₃<span>+.3Cl</span>₂<span>=...2FeCl</span>₃<span>+.3Br</span>₂