I am asked to find the mass of the cone. The cone has height 6, radius at the base 4 and the density function is $4+z$. I am asked to use cylindrical coordinates. 
For this I reason I should solve the triple integral $$\int\_0^6 \int\_0^{2\pi} \int\_0^4 (4+z)rdrd\theta dz $$ But, I know that this cannot be correct because the radius of the cone varies. How can I describe the radius of the cone?