Pi = 180°
sin 11pi/6 = sin 330° - Cadranul IV,unde sin < 0 ( si cos > 0)
=》 sin 11pi/6 < 0
cos 3pi/4 = cos 135° - Cadranul II,unde cos < 0 ( si sin > 0)
=》 cos 3pi/4 < 0
tg 4pi/3 = tg 240° - Cadranul III,unde sin < 0 si cos < 0
Cum tg=sin/cos =》tg > 0
=》 tg 4pi/3 > 0
ctg 2pi/3 = ctg 120° Cadranul II,unde sin > 0 si cos < 0
Cum ctg = cos/sin =》 ctg < 0
=》sgn( sin 11 pi/6*cos 3pi/4*tg 4pi/3*ctg 2pi/3 ) = - * - * + * -* = -
( produsul < 0 )
