5* 2tg (a/2) / (1+ tg^2 (a/2)) + (1-tg^2 (a/2)/ (1+tg^2 (a/2) ) = 5
10tg (a/2) + 1- tg^2 (a/2) = 5 +5tg^2 (a/2)
6tg^2 (a/2)-10tg(a/2)-4=0
tg(a/2) = x
6x^2 - 10x-4=0
3x^2 - 5x - 2=0
d=25+4*3*2=49
x1=2
x2=-1/3
tg (a/2)=2
a/2= arctg2+Pi*R
a1=2arctg2+2Pi*R
tg(a/2)=-1/3
a2=2arctg(-1/3)+2Pi*R
2)
sin(5x) - sin(3x) = 0
2*sin(x)*cos(4x) = 0
sin(x) = 0 или cos(4x) = 0
4x = Pi/2 + Pi*n
x=Pi*k x = Pi/8 + (Pi/4)*n
Где k и n принадлежат целым числам.