Two non-conducting spheres of radii R _ 1 and R _ 2 and carrying...

In triangle $P{C}_{1}{C}_{2}$,
$\overset{\to}{r}2 = \overset{\to}{d} + \overset{\to}{r}1$

The electrostatic field at point $P$ is,
$\overset{\to}{E} = K\left(ρ\dfrac{4}{3}\pi{R}_{1}^{3}\right)\left(\overset{\to}{r}2\right){R}_{1}^{3} + K\left(ρ\dfrac{4}{3}\pi{R}_{2}^{3}\right)\left(- \overset{\to}{r}1\right){R}_{2}^{3}$
$\overset{\to}{E} = Kρ\dfrac{4}{3}\pi\left(\overset{\to}{r}2 - \overset{\to}{r}1\right)$
$\overset{\to}{E} = \dfrac{ρ}{3{ε}_{0}}\overset{\to}{d}$