On a spacecraft two engines fire for a time of 479 s one

Question

Solve the all parts of following problem:

Problem: On a spacecraft two engines fire for a time of 479 s. One gives the craft an acceleration in the x direction of ax = 4.99 m/s², while the other produces an acceleration in the y direction of ay = 8.10 m/s2. At the end of the firing period, the craft has velocity components of vx = 3840 m/s and vy = 5210 m/s.

Part A: Find the magnitude of the initial velocity?

Part B: Find the direction of the initial velocity?

I need help to find the direction of the initial velocity and express the direction as an angle with respect to the +x axis.