Sin105°= cos105°= tg105°= ctg105°=
sin 105 = sin( 90 + 15 ) = cos 15 cos ( 90 + α ) = - sin α cos 105 = cos( 90 + 15 ) = -sin 15 tg ( 90 + α ) = -ctg α tg 105 = tg( 90 + 15 ) = -ctg 15