A helium atom (m= 6.6465 x 10^-27 kg) collides elastically with an oxygen atom (m = 2.6560x10^26kg) at rest. After the collision, the helium atom is observed to be moving with a velocity of 6.636x10^6 m/s in a direction at an angle of 84.7 relative to its original direction. The oxygen atom is observed to move at an angle of -40.4 degrees.
(a) Find the speed of the oxygen atom.
(b) Find the speed of the helium atom before the collision.