Final answer:
The calculation of total mass and center of mass for a thin wire following the curve r(t) = <cos(t), 0, sin(t)> with mass density of 4 - z kg/m³ involves integration and the application of multivariable calculus and physics.
Step-by-step explanation:
The student is attempting to find the total mass and the center of mass of a wire described by a vector function r(t) = cos(t), 0, sin(t) with a mass density of (x, y, z) = 4 - z kg/m³, where t ranges from 0 to π. To calculate the total mass, you would need to integrate the mass density along the length of the wire using the given boundaries for t. The calculation for the center of mass would involve finding the weighted average positions along the x, y, and z axes using the mass density function and the positional vector function for t. However, I must point out that the question has a typo, and the given vector function should be written in the format r(t) = <cos(t), 0, sin(t)>. Assuming that this is what was meant, it becomes a problem of multivariable calculus and physics.