An unstable nucleus with mass of 13.1 x 10^-27 kg initially at rest disintegrates into 3 particles. One of the particles, of mass 4.4 x 10^-27 moves along the positive y-axis with a speed of 5.5 x 10^6 m/s. Another particle, of mass 6.3 x 10^-27 kg moves along the positive x-axis with a speed of 3.6 x 10^6 m/s.
a) find the speed of the third particle
b) at what angle does the third particle move?