11-16+16cos^x+16cosx=0
cosx=t
16t^+16t-5=0
t=(-8+-sqrt(64+80))/16=(-8+-12)/16
t=4/16=1/4
cosx=1/4
x=arccos(1/4)+2Пk
11-16+16cos^x+16cosx=0
cosx=t
16t^+16t-5=0
t=(-8+-sqrt(64+80))/16=(-8+-12)/16
t=4/16=1/4
cosx=1/4
x=arccos(1/4)+2Пk