30°=pi/6 2x+pi/6= -pi/2+2pi*n, n∈Z 2x= -pi/2-pi/6+2pi*n, n∈Z 2x= (-2pi)/3+2pi*n, n∈Z x= -pi/3+pi*n, n∈Z n=0 -pi/3= -60° n= -1 -pi/3-pi= (-pi-3pi)/3= -4pi/3= -240°