calcular sen x, sabendose que x+y=pi\/2​

x+y=pi/4 
seny =3/5 .....cosy =4/5 
senx =w 

sen(x+y) = sen(pi/4) =V2/2 
senx.cosy+seny.cosx = v2/2 
w.4/5+3/5V(1+w²)=v2/2 
3/5V(1-w²) = v2/2-4w/5 

9(1-w²)/25 = 1/2-4wv2/5+ 16w²/25 

9(1-w²) = 25/2-20wv2+16w² 
9 -9w² =25/2 -20wv2+16w² 
25W²-20v2w+7/2=0 
delta=450 = 900/2 
Vdelta = 15V2 
w= (20v2+/-15v2)/(2*25) 


w =senx = 5V2/50 = v2/10