Flight of an Aeroplane problem

Hi, I would be really grateful to anyone who can help me with this problem...

An aeroplane flies at a constant speed of 800km per hour in a straight line from (-100, -200) to (300, 1000).

(positions are given with ref to Cartesian coordinate system whose x- and y- axes point due East and due North respectively)

I think the equation of the line of flight of the aeroplane is:

rise= 1000 -(-200) = 1200

run= 300-(-100) = 400

slope = 1200/400 = 3

so y - (-200) = 3 (x -(-100))

y = 3x -500

Am I right so far?

Next I need to find the direction of travel of the aeroplane as a bearing with the angle correct to one decimal place...I can't seem to find anything in my text books telling me how I might go about doing this!

The final part of this question is as follows. A radar station at (0, 200) has a range of 100km.

What is the equation of the circle at the limit of the radar stations range?

I also need to find the points where the line of flight of the aeroplane intersects this circle and the time during which the aeroplane is within range of the radar station in minutes to one decimal place.

Many thanks to anyone who can help!