trigonometry 3 (applications)

Two helicopters A and B are flying at constant altitudes of 600m and 800m respectively. Helicopter A is flying due south and helicopter B is flying due east.Helicopter A is now vertically below helicopter B. Suppose the speed s of helicopters A and B are 50m/s and 60m/s respectively. Find, after 20 seconds,a) the distance between the two helicopters,correct to the nearest interger;(ans:1575m)b) the angle of elevation of helicopter B from helicopter A;(ans:7.3 degree)c) the compass bearing of helicopter B from helicopter A.(ans:N50.2E)