D3.8. Determine an expression for the volume charge density associated with 4xy 2x2 2x²y each D field: (a) D = ―ax + ay - Z z2 az; (b) D = z sino ap + ρ z cos & a¿ + p sin ó̟ az; (c) Ɗ = sin 0 sin & a,. + cos 0 sin & a + cos & a‹. 4y Ans. 13 (x² + =²); 0; 0.