50.0-kg skater is traveling due east at a speed of 3.00 m/s. a 70.0-kg skater is moving due south at a speed of 7.00 m/s. they collide and hold on to each other after the collision, managing to move off at an angle θ south of east, with a speed of vf. find (a)the angle θ and (b)the speed vf, assuming that friction can be ignored.