dipole

let me compare between CH₃Cl(1) and CHCl₃(2)

the dipole moments in both 1 and 2 are additive(that can be shown by drawing the tetrahedral structures of the two compounds and then finding the directions of bond polarity for each bond). Cl tends to have a ∂- charge due its strong electro negativity and hence in 2 the Cl-Cl repulsion occurs as a result of which the Cl-C-Cl bond angle increases. we know that vector addition involves cos{bond angle}...hence as the bond angle increases the cosine value decreases and as a result the resultant dipole moment decreases !

is it the real reason for which Cl-C-Cl bond angle increases again i am wondering or its that u being so dumb to analyze the facts correctly