questioning what ρ does. What is the difference between the two equations? Let k be the angle from the positive z-axis and w be the angle from the pos x-axis parametric equation of a sphere with radius a paramet eq. 1: x = asin(k)cos(w) y = asin(k)sin(w) z= acos(k) 0≤w≤2pi 0≤k≤pi a is constant paramet equ 2: x = ρsin(k)cos(w) y = ρsin(k)sin(w) z= ρcos(k) 0≤w≤2pi 0≤k≤pi 0≤ρ≤a Is the first equation the surface of the sphere and the second would be the equation of a solid sphere? second question: Look in paint document: I originally thought that ρ = constant (which is the distance from the origin to the point) was the entire line segment from the origin to the point. But if my understanding is correct the coordinate ρ actually represents some point ρ units aways from the origin. Is this correct?