For a linear polymer molecule, the total chain length L depends

For a linear polymer molecule, the total chain length L depends on the bond length between chain atoms d, the total number of bonds in the molecule N, and the angle between adjacent backbone chain atoms ?, as follows:

Furthermore, the average end-to-end distance for a series of polymer molecules r in Figure is equal to

A linear polytetrafluoroethylene has a number-average molecular weight of 500,000 g/mol; compute average values of L and r for this material.