Cos²(2п-t)+cos²(2п+t)

1.cos^2(\pi+t)+cos^2(\pi-t)= =cos(\pi+t)*cos(\pi+t)+cos(\pi-t)*cos(\pi-t)= =(-cos(t))^2+(-cos(t))^2=2cos^2(t) 2. cos(2\pi-t)-sin(3\pi/2+t)=1 cost+cost=1 2cost=1 cost=1/2; t=\pi/3 3. sin(2\pi-t)-cos(3\pi+t)-1=0 -sint-cos(\pi+t)=-1 -sint+cost=-1 sint-cost=1 sint [-1;1]; cos[-1;1] => sint=1: cost=0 t=\pi/2