A cricket ball travelling north at 100km/h is deflected so that it travels north-east at 100km/h. What is the change in velocity of the cricket ball?

Change = 100km[45o] - 100km[90o].

100*Cos45 + 100*sin45(i) - 100i =
70.7 + 70.7i - 100i = 70.7 - 29.3i = 76.5km[-22.5o] = 76.5km[22.5o] S. of E.

Change = 76.5 km.