Ответы и объяснения

2013-06-23T09:45:09+04:00

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