1-cos0,8x=sin0.4x 0.4x=t 1-cos2t=sint 1-cos2t=2sin^2(t) => 2sin^2(t)=sint
sint(2sint-1)=0 sint=0 sint=1/2 t=2pin t2=pi/6+2pim t3=5pi/6+2pim
0.4=2/5 2/5x=2pin x=5pin 2/5x2=pi/6+2pim *(5/2) x2=5pi/12+5pim x3=25/12pi+5pim
x3=25/12pi=25*180/12=25*15=375 (- (350-411)