The component of a vector r along X-axis will have maximum value, if [NCERT Exemplar]

Let r makes an angle 0 with positive X-axis, so component of r along X-axis,rX=|r|cosθrXmaximum =|r|(cosθ)maximum =|r|cos0°∵cosθ is maximum, if θ=0°=|r| As θ=0°i.e. r is along positive X-axis.