In regards to 2-a:
First find the measure of BC by the pythagorean theorem
so what do ya need? Well, you need
but
once you have found that value, you plug what you know into the above formula to find .
Then with this information, the Law Of Cosines tells us that if we have 3 sides of an oblique triangle, we can know the value of the angles.
Here's the formula
so let and let and let where cosine of gamma =
Plug all this stuff in and slove your triangle!