|(1,2)=3x2|(1,2)=3 Therefore, required value of θ is −cotϕ=−
1
3
In the above diagram, θ is to be considered as the angle made by tangent with y-axis and not θ′ [for e.g., when we say angle made by a line with x-axis, it is the angle measured from x-axis to the line in anticlockwise direction, unless mentioned otherwise]
Here we consider θ as the angle made by the line with positive x-axis and not θ'