sin(2*a) = 2*sin(a)*cos(a)
sin(a) = (1-(cos(a))^2)^(1/2) = (1-64/289)^(1/2) = ((289 - 64)/289)^(1/2) = (225/289)^(1/2) =
= 1) 15/17
2)-15/17
так как 3* pi/2 > a > 2* pi то выбираем sin(a) = -15/17
sin(2*a) = 2*sin(a)*cos(a) = 2* (-15/17) * (8/17) = -240/289
sin(2*a) = 2*sin(a)*cos(a)
sin(a) = (1-(cos(a))^2)^(1/2) = (1-64/289)^(1/2) = ((289 - 64)/289)^(1/2) = (225/289)^(1/2) =
= 1) 15/17
2)-15/17
так как 3* pi/2 > a > 2* pi то выбираем sin(a) = -15/17
sin(2*a) = 2*sin(a)*cos(a) = 2* (-15/17) * (8/17) = -240/289