Question

cos²(2п-t)+cos²(2п+t)

Answer 1

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(2pi-t)-sin(3pi/2+t)=1
cost+cost=1
2cost=1
cost=1/2; t=pi/3
3. sin(2pi-t)-cos(3pi+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