Derive (18) as follows. Squaring (14) and integrating from−1to1, obtainIntegrating the lef...

Derive (18) as follows. Squaring (14) and integrating from−1to1, obtain

Integrating the left side, and using the orthogonality relation (9) to simplify the right side, obtain

Finally, expanding the left-hand side in a Taylor series inr,show that (18) follows.