1
arccos(-1/2)=2π/3
2
arcsin(-√2/2)=-π/4
3
cos(π/2-arcsin1/2)=sin(arcsin1/2)=1/2
4
2arccos(-√3/2)-6arccos1/2=2*5π/6-6*π/3=5π/3-6π/3=-π/3
5
arcsin(x+3)=-π/3
-π/2-3-π/2arcsin(x+3)=arcsin(-√3/2)
x+3=-√3/2
x=-3-√3/2=(-(6+√3)/2
6
3arccos²x-5arccosx+2=0
arccosx=a
3a²-5a+2=0
D=25-24=1
a1=(5-1)/6=2/3⇒arccosx=2/3⇒x=cos2/3≈48гр 11мин
a2=(5+1)/6=1⇒arccosx=1⇒x=0