A bird flies 400 m due north and then 300 m due south and then flies 1200 m upward, the net displacement is

Consider a horizontal plane (contains north south east west direction ). Let's consider a point "A" which is starting point  firstly it travels 400 m north from A and then 300 m south ..it implies it is 100 meter far from point "A" .then it travels 1200 meter vertically upward (imagine like coming out of horizontal plane we have considered) and now displacement(x) would be distance between point A" and point 1200 meter above plane .x^2=(1200)^2+(100)^2

X=1204.2 metres