Sin(4x+π/2)=-√2/2
4x+π/2=(-1)^k * arcsin(-√2/2) + πk, k∈Z
4x+π/2=(-1)^(k+1) * π/4 + πk, k∈Z
4x=(-1)^(k+1) * π/4 -π/2+ πk, k∈Z
х=(-1)^(k+1) * π -2π + 4πk, k∈Z.
√(2/2)=√1=1
7arcsin(-1)+9arccos1+10arctg(-1)=7*(-π/2)+9*0+10*(-π/4)=-7π/2-5π/2=-6π
(cos(П/4+t)+cos(П/4-t))^2=1/2[(cost-sint)^2+(cost+sint)^2]+2cos(П/4+t)*cos(П/4-t)=
=1/2[1-2costsint+1+2sintcost]+2cos(П/4+t)*cos(П/4-t)=p^2
2cos(П/4+t)*cos(П/4-t)=p^2-1
cos(П/4+t)*cos(П/4-t)=(p^2-1)/2