Vector algebra

Given two vectors, \vec{a} and \vec{b} with norms, \left|\vec{a}\right|=a, \left|\vec{b}\right|=b and the angle \phi between them,

1.Find \left|\vec{a}+\vec{b}\right|.
2. Find the angle \psi between \vec{a}+\vec{b} and \vec{a}.