Find the equation of a straight line on which length of perpendicular from the origin is four units and the line makes an angle of 120° with the positive direction of x-axis.
Given that length of the perpendicular from the origin is 4 units and line makes an angle with positive direction of x-axis
∠BAX=120
∠BA0=180-120=60
∠MAO=60
Now in triangle AMO ∠MAO+∠AOM+∠OMA=1800
600+θ+ 900=1800
θ=300 ∠AOM= 300
x cosθ+ysinθ=p
xcos 300+ysin300=4