need some help for this quantum mechanics problem

Hi, this is a problem from my engineering class, which currently I have no clue how to start this, so I'm wondering if anyone can give me some hints so I can get start on this problem. Any help will be appricated. thanks.

Part C (10 points) One of the first equations students taking quantum mechanics are asked to solve is:

ktan (kL/2) = sqrt (b^2-k^2)

Write a program which prompts the user to enter values for b and L (both positive) and then calculates k. Some

combinations of b and L give multiple solutions for k. There will always be exactly one solution for k between 0 and 3.14/L , this is the solution you should find. The name of this program must be QWell.c